restructure test

- Add shard request manager

.github/workflows/diff.yaml

@@ -130,7 +130,7 @@ jobs:
           source /opt/toolchain-v4/activate
 
           # Restrict clang-tidy results only to the modified parts
-          git diff -U0 ${{ env.BASE_BRANCH }}... -- src | ./tools/github/clang-tidy/clang-tidy-diff.py -p 1 -j $THREADS -path build | tee ./build/clang_tidy_output.txt
+          git diff -U0 ${{ env.BASE_BRANCH }}... -- src | ./tools/github/clang-tidy/clang-tidy-diff.py -p 1 -j $THREADS -extra-arg="-DMG_CLANG_TIDY_CHECK" -path build | tee ./build/clang_tidy_output.txt
 
           # Fail if any warning is reported
           ! cat ./build/clang_tidy_output.txt | ./tools/github/clang-tidy/grep_error_lines.sh > /dev/null
@@ -171,7 +171,7 @@ jobs:
 
           # Run leftover CTest tests (all except unit and benchmark tests).
           cd build
-          ctest -E "(memgraph__unit|memgraph__benchmark)" --output-on-failure
+          ctest -E "(memgraph__unit|memgraph__benchmark|memgraph__simulation)" --output-on-failure
 
       - name: Run drivers tests
         run: |
@@ -262,6 +262,15 @@ jobs:
           cd build
           ctest -R memgraph__unit --output-on-failure -j$THREADS
 
+      - name: Run simulation tests
+        run: |
+          # Activate toolchain.
+          source /opt/toolchain-v4/activate
+
+          # Run unit tests.
+          cd build
+          ctest -R memgraph__simulation --output-on-failure -j$THREADS
+
       - name: Run e2e tests
         run: |
           # TODO(gitbuda): Setup mgclient and pymgclient properly.

.github/workflows/full_clang_tidy.yaml

@@ -39,7 +39,7 @@ jobs:
           source /opt/toolchain-v4/activate
 
           # The results are also written to standard output in order to retain them in the logs
-          ./tools/github/clang-tidy/run-clang-tidy.py -p build -j $THREADS -clang-tidy-binary=/opt/toolchain-v4/bin/clang-tidy "$PWD/src/*" |
+          ./tools/github/clang-tidy/run-clang-tidy.py -p build -j $THREADS -extra-arg="-DMG_CLANG_TIDY_CHECK" -clang-tidy-binary=/opt/toolchain-v4/bin/clang-tidy "$PWD/src/*" |
             tee ./build/full_clang_tidy_output.txt
 
       - name: Summarize clang-tidy results

.gitignore

@@ -24,6 +24,7 @@ cmake/DownloadProject/
 dist/
 src/query/frontend/opencypher/generated/
 src/query/v2/frontend/opencypher/generated/
+src/parser/opencypher/generated
 tags
 ve/
 ve3/
@@ -53,6 +54,7 @@ src/distributed/token_sharing_rpc_messages.hpp
 src/distributed/updates_rpc_messages.hpp
 src/query/v2/frontend/ast/ast.hpp
 src/query/frontend/ast/ast.hpp
+src/storage/v3/bindings/ast/ast.hpp
 src/query/distributed/frontend/ast/ast_serialization.hpp
 src/query/v2/distributed/frontend/ast/ast_serialization.hpp
 src/durability/distributed/state_delta.hpp
@@ -60,12 +62,15 @@ src/durability/single_node/state_delta.hpp
 src/durability/single_node_ha/state_delta.hpp
 src/query/frontend/semantic/symbol.hpp
 src/query/v2/frontend/semantic/symbol.hpp
+src/expr/semantic/symbol.hpp
 src/query/distributed/frontend/semantic/symbol_serialization.hpp
 src/query/v2/distributed/frontend/semantic/symbol_serialization.hpp
 src/query/distributed/plan/ops.hpp
 src/query/v2/distributed/plan/ops.hpp
 src/query/plan/operator.hpp
 src/query/v2/plan/operator.hpp
+src/parser/opencypher/generated
+src/expr/semantic/symbol.hpp
 src/raft/log_entry.hpp
 src/raft/raft_rpc_messages.hpp
 src/raft/snapshot_metadata.hpp

src/CMakeLists.txt

@@ -5,6 +5,7 @@ add_subdirectory(lisp)
 add_subdirectory(utils)
 add_subdirectory(requests)
 add_subdirectory(io)
+add_subdirectory(io/simulator)
 add_subdirectory(kvstore)
 add_subdirectory(telemetry)
 add_subdirectory(communication)
@@ -17,6 +18,9 @@ add_subdirectory(query/v2)
 add_subdirectory(slk)
 add_subdirectory(rpc)
 add_subdirectory(auth)
+add_subdirectory(parser)
+add_subdirectory(expr)
+add_subdirectory(coordinator)
 
 if (MG_ENTERPRISE)
   add_subdirectory(audit)

src/coordinator/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(coordinator_src_files
+    coordinator.cpp
+    shard_map.cpp)
+
+find_package(fmt REQUIRED)
+find_package(Threads REQUIRED)
+
+add_library(mg-coordinator STATIC ${coordinator_src_files})
+target_link_libraries(mg-coordinator stdc++fs Threads::Threads fmt::fmt mg-utils mg-storage-v3)

src/coordinator/coordinator.cpp

@@ -0,0 +1,129 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include <coordinator/coordinator.hpp>
+
+namespace memgraph::coordinator {
+
+CoordinatorWriteResponses Coordinator::ApplyWrite(HeartbeatRequest &&heartbeat_request) {
+  spdlog::info("Coordinator handling HeartbeatRequest");
+
+  // add this storage engine to any under-replicated shards that it is not already a part of
+
+  auto initializing_rsms_for_shard_manager =
+      shard_map_.AssignShards(heartbeat_request.from_storage_manager, heartbeat_request.initialized_rsms);
+
+  return HeartbeatResponse{
+      .shards_to_initialize = initializing_rsms_for_shard_manager,
+  };
+}
+
+CoordinatorWriteResponses Coordinator::ApplyWrite(HlcRequest &&hlc_request) {
+  HlcResponse res{};
+
+  auto hlc_shard_map = shard_map_.GetHlc();
+
+  MG_ASSERT(!(hlc_request.last_shard_map_version.logical_id > hlc_shard_map.logical_id));
+
+  res.new_hlc = Hlc{
+      .logical_id = ++highest_allocated_timestamp_,
+      // TODO(tyler) probably pass some more context to the Coordinator here
+      // so that we can use our wall clock and enforce monotonicity.
+      // .coordinator_wall_clock = io_.Now(),
+  };
+
+  // Allways return fresher shard_map for now.
+  res.fresher_shard_map = std::make_optional(shard_map_);
+
+  return res;
+}
+
+CoordinatorWriteResponses Coordinator::ApplyWrite(AllocateEdgeIdBatchRequest &&ahr) {
+  AllocateEdgeIdBatchResponse res{};
+
+  uint64_t low = highest_allocated_edge_id_;
+
+  highest_allocated_edge_id_ += ahr.batch_size;
+
+  uint64_t high = highest_allocated_edge_id_;
+
+  res.low = low;
+  res.high = high;
+
+  return res;
+}
+
+/// This splits the shard immediately beneath the provided
+/// split key, keeping the assigned peers identical for now,
+/// but letting them be gradually migrated over time.
+CoordinatorWriteResponses Coordinator::ApplyWrite(SplitShardRequest &&split_shard_request) {
+  SplitShardResponse res{};
+
+  if (split_shard_request.previous_shard_map_version != shard_map_.shard_map_version) {
+    res.success = false;
+  } else {
+    res.success = shard_map_.SplitShard(split_shard_request.previous_shard_map_version, split_shard_request.label_id,
+                                        split_shard_request.split_key);
+  }
+
+  return res;
+}
+
+/// This adds the provided storage engine to the standby storage engine pool,
+/// which can be used to rebalance storage over time.
+CoordinatorWriteResponses Coordinator::ApplyWrite(
+    RegisterStorageEngineRequest && /* register_storage_engine_request */) {
+  RegisterStorageEngineResponse res{};
+  // TODO
+
+  return res;
+}
+
+/// This begins the process of draining the provided storage engine from all raft
+/// clusters that it might be participating in.
+CoordinatorWriteResponses Coordinator::ApplyWrite(
+    DeregisterStorageEngineRequest && /* register_storage_engine_request */) {
+  DeregisterStorageEngineResponse res{};
+  // TODO
+
+  return res;
+}
+
+CoordinatorWriteResponses Coordinator::ApplyWrite(InitializeLabelRequest &&initialize_label_request) {
+  InitializeLabelResponse res{};
+
+  std::optional<LabelId> new_label_id = shard_map_.InitializeNewLabel(
+      initialize_label_request.label_name, initialize_label_request.schema, initialize_label_request.replication_factor,
+      initialize_label_request.last_shard_map_version);
+
+  if (new_label_id) {
+    res.new_label_id = new_label_id.value();
+    res.fresher_shard_map = std::nullopt;
+    res.success = true;
+  } else {
+    res.fresher_shard_map = shard_map_;
+    res.success = false;
+  }
+
+  return res;
+}
+
+CoordinatorWriteResponses Coordinator::ApplyWrite(AllocatePropertyIdsRequest &&allocate_property_ids_request) {
+  AllocatePropertyIdsResponse res{};
+
+  auto property_ids = shard_map_.AllocatePropertyIds(allocate_property_ids_request.property_names);
+
+  res.property_ids = property_ids;
+
+  return res;
+}
+
+}  // namespace memgraph::coordinator

src/coordinator/coordinator.hpp

@@ -0,0 +1,196 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <optional>
+#include <set>
+#include <string>
+#include <unordered_set>
+#include <variant>
+#include <vector>
+
+#include <boost/uuid/uuid.hpp>
+
+#include <coordinator/hybrid_logical_clock.hpp>
+#include <coordinator/shard_map.hpp>
+#include <io/simulator/simulator.hpp>
+#include <io/time.hpp>
+#include <io/transport.hpp>
+#include <storage/v3/id_types.hpp>
+#include <storage/v3/schemas.hpp>
+
+namespace memgraph::coordinator {
+
+using memgraph::io::Address;
+using memgraph::storage::v3::LabelId;
+using memgraph::storage::v3::PropertyId;
+using memgraph::storage::v3::SchemaProperty;
+using SimT = memgraph::io::simulator::SimulatorTransport;
+using PrimaryKey = std::vector<PropertyValue>;
+
+struct HlcRequest {
+  Hlc last_shard_map_version;
+};
+
+struct HlcResponse {
+  Hlc new_hlc;
+  std::optional<ShardMap> fresher_shard_map;
+};
+
+struct GetShardMapRequest {
+  // No state
+};
+
+struct GetShardMapResponse {
+  ShardMap shard_map;
+};
+
+struct AllocateHlcBatchRequest {
+  Hlc low;
+  Hlc high;
+};
+
+struct AllocateHlcBatchResponse {
+  bool success;
+  Hlc low;
+  Hlc high;
+};
+
+struct AllocateEdgeIdBatchRequest {
+  size_t batch_size;
+};
+
+struct AllocateEdgeIdBatchResponse {
+  uint64_t low;
+  uint64_t high;
+};
+
+struct AllocatePropertyIdsRequest {
+  std::vector<std::string> property_names;
+};
+
+struct AllocatePropertyIdsResponse {
+  std::map<std::string, PropertyId> property_ids;
+};
+
+struct SplitShardRequest {
+  Hlc previous_shard_map_version;
+  LabelId label_id;
+  PrimaryKey split_key;
+};
+
+struct SplitShardResponse {
+  bool success;
+};
+
+struct RegisterStorageEngineRequest {
+  Address address;
+};
+
+struct RegisterStorageEngineResponse {
+  bool success;
+};
+
+struct DeregisterStorageEngineRequest {
+  Address address;
+};
+
+struct DeregisterStorageEngineResponse {
+  bool success;
+};
+
+struct InitializeLabelRequest {
+  std::string label_name;
+  std::vector<SchemaProperty> schema;
+  size_t replication_factor;
+  Hlc last_shard_map_version;
+};
+
+struct InitializeLabelResponse {
+  bool success;
+  LabelId new_label_id;
+  std::optional<ShardMap> fresher_shard_map;
+};
+
+struct HeartbeatRequest {
+  Address from_storage_manager;
+  std::set<boost::uuids::uuid> initialized_rsms;
+};
+
+struct HeartbeatResponse {
+  std::vector<ShardToInitialize> shards_to_initialize;
+};
+
+using CoordinatorWriteRequests =
+    std::variant<HlcRequest, AllocateEdgeIdBatchRequest, SplitShardRequest, RegisterStorageEngineRequest,
+                 DeregisterStorageEngineRequest, InitializeLabelRequest, AllocatePropertyIdsRequest, HeartbeatRequest>;
+using CoordinatorWriteResponses = std::variant<HlcResponse, AllocateEdgeIdBatchResponse, SplitShardResponse,
+                                               RegisterStorageEngineResponse, DeregisterStorageEngineResponse,
+                                               InitializeLabelResponse, AllocatePropertyIdsResponse, HeartbeatResponse>;
+
+using CoordinatorReadRequests = std::variant<GetShardMapRequest>;
+using CoordinatorReadResponses = std::variant<GetShardMapResponse>;
+
+class Coordinator {
+ public:
+  explicit Coordinator(ShardMap sm) : shard_map_{std::move(sm)} {}
+
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static
+  CoordinatorReadResponses Read(CoordinatorReadRequests requests) {
+    return std::visit([&](auto &&request) { return HandleRead(std::forward<decltype(request)>(request)); },
+                      std::move(requests));  // NOLINT(hicpp-move-const-arg,performance-move-const-arg)
+  }
+
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static
+  CoordinatorWriteResponses Apply(CoordinatorWriteRequests requests) {
+    return std::visit([&](auto &&request) mutable { return ApplyWrite(std::forward<decltype(request)>(request)); },
+                      std::move(requests));
+  }
+
+ private:
+  ShardMap shard_map_;
+  uint64_t highest_allocated_timestamp_;
+
+  /// Query engines need to periodically request batches of unique edge IDs.
+  uint64_t highest_allocated_edge_id_;
+
+  CoordinatorReadResponses HandleRead(GetShardMapRequest && /* get_shard_map_request */) {
+    GetShardMapResponse res;
+    res.shard_map = shard_map_;
+    return res;
+  }
+
+  CoordinatorWriteResponses ApplyWrite(HeartbeatRequest &&heartbeat_request);
+
+  CoordinatorWriteResponses ApplyWrite(HlcRequest &&hlc_request);
+
+  CoordinatorWriteResponses ApplyWrite(AllocateEdgeIdBatchRequest &&ahr);
+
+  /// This splits the shard immediately beneath the provided
+  /// split key, keeping the assigned peers identical for now,
+  /// but letting them be gradually migrated over time.
+  CoordinatorWriteResponses ApplyWrite(SplitShardRequest &&split_shard_request);
+
+  /// This adds the provided storage engine to the standby storage engine pool,
+  /// which can be used to rebalance storage over time.
+  static CoordinatorWriteResponses ApplyWrite(RegisterStorageEngineRequest && /* register_storage_engine_request */);
+
+  /// This begins the process of draining the provided storage engine from all raft
+  /// clusters that it might be participating in.
+  static CoordinatorWriteResponses ApplyWrite(DeregisterStorageEngineRequest && /* register_storage_engine_request */);
+
+  CoordinatorWriteResponses ApplyWrite(InitializeLabelRequest &&initialize_label_request);
+
+  CoordinatorWriteResponses ApplyWrite(AllocatePropertyIdsRequest &&allocate_property_ids_request);
+};
+
+}  // namespace memgraph::coordinator

src/coordinator/coordinator_client.hpp

@@ -0,0 +1,24 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "coordinator/coordinator.hpp"
+#include "io/rsm/rsm_client.hpp"
+
+namespace memgraph::coordinator {
+
+using memgraph::io::rsm::RsmClient;
+
+template <typename IoImpl>
+using CoordinatorClient = RsmClient<IoImpl, CoordinatorWriteRequests, CoordinatorWriteResponses,
+                                    CoordinatorReadRequests, CoordinatorReadResponses>;
+}  // namespace memgraph::coordinator

src/coordinator/coordinator_rsm.hpp

@@ -0,0 +1,23 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "coordinator/coordinator.hpp"
+#include "io/rsm/raft.hpp"
+
+namespace memgraph::coordinator {
+
+template <typename IoImpl>
+using CoordinatorRsm = memgraph::io::rsm::Raft<IoImpl, Coordinator, CoordinatorWriteRequests, CoordinatorWriteResponses,
+                                               CoordinatorReadRequests, CoordinatorReadResponses>;
+
+}  // namespace memgraph::coordinator

src/coordinator/hybrid_logical_clock.hpp

@@ -0,0 +1,36 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <compare>
+
+#include "io/time.hpp"
+
+namespace memgraph::coordinator {
+
+using Time = memgraph::io::Time;
+
+/// Hybrid-logical clock
+struct Hlc {
+  uint64_t logical_id;
+  Time coordinator_wall_clock;
+
+  auto operator<=>(const Hlc &other) const { return logical_id <=> other.logical_id; }
+
+  bool operator==(const Hlc &other) const = default;
+  bool operator<(const Hlc &other) const = default;
+  bool operator==(const uint64_t other) const { return logical_id == other; }
+  bool operator<(const uint64_t other) const { return logical_id < other; }
+  bool operator>=(const uint64_t other) const { return logical_id >= other; }
+};
+
+}  // namespace memgraph::coordinator

src/coordinator/shard_map.cpp

@@ -0,0 +1,90 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "coordinator/shard_map.hpp"
+#include "storage/v3/temporal.hpp"
+
+namespace memgraph::coordinator {
+
+using memgraph::common::SchemaType;
+using memgraph::storage::v3::TemporalData;
+using memgraph::storage::v3::TemporalType;
+
+PrimaryKey SchemaToMinKey(const std::vector<SchemaProperty> &schema) {
+  PrimaryKey ret{};
+
+  const int64_t min_int = std::numeric_limits<int64_t>::min();
+
+  const TemporalData date{TemporalType::Date, min_int};
+  const TemporalData local_time{TemporalType::LocalTime, min_int};
+  const TemporalData local_date_time{TemporalType::LocalDateTime, min_int};
+  const TemporalData duration{TemporalType::Duration, min_int};
+
+  for (const auto &schema_property : schema) {
+    switch (schema_property.type) {
+      case SchemaType::BOOL:
+        ret.emplace_back(PropertyValue(false));
+        break;
+      case SchemaType::INT:
+        ret.emplace_back(PropertyValue(min_int));
+        break;
+      case SchemaType::STRING:
+        ret.emplace_back(PropertyValue(""));
+        break;
+      case SchemaType::DATE:
+        ret.emplace_back(PropertyValue(date));
+        break;
+      case SchemaType::LOCALTIME:
+        ret.emplace_back(PropertyValue(local_time));
+        break;
+      case SchemaType::LOCALDATETIME:
+        ret.emplace_back(PropertyValue(local_date_time));
+        break;
+      case SchemaType::DURATION:
+        ret.emplace_back(PropertyValue(duration));
+        break;
+    }
+  }
+
+  return ret;
+}
+
+std::optional<LabelId> ShardMap::InitializeNewLabel(std::string label_name, std::vector<SchemaProperty> schema,
+                                                    size_t replication_factor, Hlc last_shard_map_version) {
+  if (shard_map_version != last_shard_map_version || labels.contains(label_name)) {
+    return std::nullopt;
+  }
+
+  const LabelId label_id = LabelId::FromUint(++max_label_id);
+
+  labels.emplace(std::move(label_name), label_id);
+
+  PrimaryKey initial_key = SchemaToMinKey(schema);
+  Shard empty_shard = {};
+
+  Shards shards = {
+      {initial_key, empty_shard},
+  };
+
+  LabelSpace label_space{
+      .schema = std::move(schema),
+      .shards = shards,
+      .replication_factor = replication_factor,
+  };
+
+  label_spaces.emplace(label_id, label_space);
+
+  IncrementShardMapVersion();
+
+  return label_id;
+}
+
+}  // namespace memgraph::coordinator

src/coordinator/shard_map.hpp

@@ -0,0 +1,276 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <limits>
+#include <map>
+#include <set>
+#include <vector>
+
+#include <boost/uuid/uuid.hpp>
+#include <boost/uuid/uuid_generators.hpp>
+
+#include "common/types.hpp"
+#include "coordinator/hybrid_logical_clock.hpp"
+#include "io/address.hpp"
+#include "storage/v3/config.hpp"
+#include "storage/v3/id_types.hpp"
+#include "storage/v3/property_value.hpp"
+#include "storage/v3/schemas.hpp"
+#include "storage/v3/temporal.hpp"
+
+namespace memgraph::coordinator {
+
+using memgraph::io::Address;
+using memgraph::storage::v3::Config;
+using memgraph::storage::v3::LabelId;
+using memgraph::storage::v3::PropertyId;
+using memgraph::storage::v3::PropertyValue;
+using memgraph::storage::v3::SchemaProperty;
+
+enum class Status : uint8_t {
+  CONSENSUS_PARTICIPANT,
+  INITIALIZING,
+  // TODO(tyler) this will possibly have more states,
+  // depending on the reconfiguration protocol that we
+  // implement.
+};
+
+struct AddressAndStatus {
+  memgraph::io::Address address;
+  Status status;
+  friend bool operator<(const AddressAndStatus &lhs, const AddressAndStatus &rhs) { return lhs.address < rhs.address; }
+};
+
+using PrimaryKey = std::vector<PropertyValue>;
+using Shard = std::vector<AddressAndStatus>;
+using Shards = std::map<PrimaryKey, Shard>;
+using LabelName = std::string;
+using PropertyName = std::string;
+using PropertyMap = std::map<PropertyName, PropertyId>;
+
+struct ShardToInitialize {
+  boost::uuids::uuid uuid;
+  LabelId label_id;
+  PrimaryKey min_key;
+  std::optional<PrimaryKey> max_key;
+  Config config;
+};
+
+PrimaryKey SchemaToMinKey(const std::vector<SchemaProperty> &schema);
+
+struct LabelSpace {
+  std::vector<SchemaProperty> schema;
+  std::map<PrimaryKey, Shard> shards;
+  size_t replication_factor;
+};
+
+struct ShardMap {
+  Hlc shard_map_version;
+  uint64_t max_property_id;
+  std::map<PropertyName, PropertyId> properties;
+  uint64_t max_label_id;
+  std::map<LabelName, LabelId> labels;
+  std::map<LabelId, LabelSpace> label_spaces;
+  std::map<LabelId, std::vector<SchemaProperty>> schemas;
+
+  Shards GetShards(const LabelName &label) {
+    const auto id = labels.at(label);
+    auto &shards = label_spaces.at(id).shards;
+    return shards;
+  }
+
+  // TODO(gabor) later we will want to update the wallclock time with
+  // the given Io<impl>'s time as well
+  Hlc IncrementShardMapVersion() noexcept {
+    ++shard_map_version.logical_id;
+    return shard_map_version;
+  }
+
+  Hlc GetHlc() const noexcept { return shard_map_version; }
+
+  // Returns the shard UUIDs that have been assigned but not yet acknowledged for this storage manager
+  std::vector<ShardToInitialize> AssignShards(Address storage_manager, std::set<boost::uuids::uuid> initialized) {
+    std::vector<ShardToInitialize> ret{};
+
+    bool mutated = false;
+
+    for (auto &[label_id, label_space] : label_spaces) {
+      for (auto &[low_key, shard] : label_space.shards) {
+        // TODO(tyler) avoid these triple-nested loops by having the heartbeat include better info
+        bool machine_contains_shard = false;
+
+        for (auto &aas : shard) {
+          if (initialized.contains(aas.address.unique_id)) {
+            spdlog::info("marking shard as full consensus participant: {}", aas.address.unique_id);
+            aas.status = Status::CONSENSUS_PARTICIPANT;
+            machine_contains_shard = true;
+          } else {
+            const bool same_machine = aas.address.last_known_ip == storage_manager.last_known_ip &&
+                                      aas.address.last_known_port == storage_manager.last_known_port;
+            if (same_machine) {
+              machine_contains_shard = true;
+              ret.push_back(ShardToInitialize{
+                  .uuid = aas.address.unique_id,
+                  .label_id = label_id,
+                  .min_key = low_key,
+                  .max_key = std::nullopt,
+                  .config = Config{},
+              });
+            }
+          }
+        }
+
+        if (!machine_contains_shard && shard.size() < label_space.replication_factor) {
+          Address address = storage_manager;
+
+          // TODO(tyler) use deterministic UUID so that coordinators don't diverge here
+          address.unique_id = boost::uuids::uuid{boost::uuids::random_generator()()},
+
+          ret.push_back(ShardToInitialize{
+              .uuid = address.unique_id,
+              .label_id = label_id,
+              .min_key = low_key,
+              .max_key = std::nullopt,
+              .config = Config{},
+          });
+
+          AddressAndStatus aas = {
+              .address = address,
+              .status = Status::INITIALIZING,
+          };
+
+          shard.emplace_back(aas);
+        }
+      }
+    }
+
+    if (mutated) {
+      IncrementShardMapVersion();
+    }
+
+    return ret;
+  }
+
+  bool SplitShard(Hlc previous_shard_map_version, LabelId label_id, const PrimaryKey &key) {
+    if (previous_shard_map_version != shard_map_version) {
+      return false;
+    }
+
+    auto &label_space = label_spaces.at(label_id);
+    auto &shards_in_map = label_space.shards;
+
+    MG_ASSERT(!shards_in_map.empty());
+    MG_ASSERT(!shards_in_map.contains(key));
+    MG_ASSERT(label_spaces.contains(label_id));
+
+    // Finding the Shard that the new PrimaryKey should map to.
+    auto prev = std::prev(shards_in_map.upper_bound(key));
+    Shard duplicated_shard = prev->second;
+
+    // Apply the split
+    shards_in_map[key] = duplicated_shard;
+
+    return true;
+  }
+
+  std::optional<LabelId> InitializeNewLabel(std::string label_name, std::vector<SchemaProperty> schema,
+                                            size_t replication_factor, Hlc last_shard_map_version);
+
+  void AddServer(Address server_address) {
+    // Find a random place for the server to plug in
+  }
+
+  LabelId GetLabelId(const std::string &label) const { return labels.at(label); }
+
+  Shards GetShardsForRange(const LabelName &label_name, const PrimaryKey &start_key, const PrimaryKey &end_key) const {
+    MG_ASSERT(start_key <= end_key);
+    MG_ASSERT(labels.contains(label_name));
+
+    LabelId label_id = labels.at(label_name);
+
+    const auto &label_space = label_spaces.at(label_id);
+
+    const auto &shards_for_label = label_space.shards;
+
+    MG_ASSERT(shards_for_label.begin()->first <= start_key,
+              "the ShardMap must always contain a minimal key that is less than or equal to any requested key");
+
+    auto it = std::prev(shards_for_label.upper_bound(start_key));
+    const auto end_it = shards_for_label.upper_bound(end_key);
+
+    Shards shards{};
+
+    std::copy(it, end_it, std::inserter(shards, shards.end()));
+
+    return shards;
+  }
+
+  Shard GetShardForKey(const LabelName &label_name, const PrimaryKey &key) const {
+    MG_ASSERT(labels.contains(label_name));
+
+    LabelId label_id = labels.at(label_name);
+
+    const auto &label_space = label_spaces.at(label_id);
+
+    MG_ASSERT(label_space.shards.begin()->first <= key,
+              "the ShardMap must always contain a minimal key that is less than or equal to any requested key");
+
+    return std::prev(label_space.shards.upper_bound(key))->second;
+  }
+
+  Shard GetShardForKey(const LabelId &label_id, const PrimaryKey &key) const {
+    MG_ASSERT(label_spaces.contains(label_id));
+
+    const auto &label_space = label_spaces.at(label_id);
+
+    MG_ASSERT(label_space.shards.begin()->first <= key,
+              "the ShardMap must always contain a minimal key that is less than or equal to any requested key");
+
+    return std::prev(label_space.shards.upper_bound(key))->second;
+  }
+
+  PropertyMap AllocatePropertyIds(const std::vector<PropertyName> &new_properties) {
+    PropertyMap ret{};
+
+    bool mutated = false;
+
+    for (const auto &property_name : new_properties) {
+      if (properties.contains(property_name)) {
+        auto property_id = properties.at(property_name);
+        ret.emplace(property_name, property_id);
+      } else {
+        mutated = true;
+
+        const PropertyId property_id = PropertyId::FromUint(++max_property_id);
+        ret.emplace(property_name, property_id);
+        properties.emplace(property_name, property_id);
+      }
+    }
+
+    if (mutated) {
+      IncrementShardMapVersion();
+    }
+
+    return ret;
+  }
+
+  std::optional<PropertyId> GetPropertyId(const std::string &property_name) const {
+    if (properties.contains(property_name)) {
+      return properties.at(property_name);
+    }
+
+    return std::nullopt;
+  }
+};
+
+}  // namespace memgraph::coordinator

src/expr/CMakeLists.txt

@@ -0,0 +1,20 @@
+define_add_lcp(add_lcp_expr lcp_expr_cpp_files generated_lcp_expr_files)
+
+add_lcp_expr(semantic/symbol.lcp)
+
+add_custom_target(generate_lcp_expr DEPENDS ${generated_lcp_expr_files})
+
+set(mg_expr_sources
+    ${lcp_expr_cpp_files}
+    parsing.cpp)
+
+find_package(Boost REQUIRED)
+
+add_library(mg-expr STATIC ${mg_expr_sources})
+add_dependencies(mg-expr generate_lcp_expr)
+target_include_directories(mg-expr PUBLIC ${CMAKE_SOURCE_DIR}/include)
+target_include_directories(mg-expr PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+target_include_directories(mg-expr PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/ast)
+target_include_directories(mg-expr PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/interpret)
+target_include_directories(mg-expr PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/semantic)
+target_link_libraries(mg-expr cppitertools Boost::headers mg-utils mg-parser)

src/expr/ast.hpp

@@ -0,0 +1,35 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+#pragma once
+
+#ifndef MG_AST_INCLUDE_PATH
+#ifdef MG_CLANG_TIDY_CHECK
+// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define MG_AST_INCLUDE_PATH "query/v2/frontend/ast/ast.hpp"
+#else
+#error Missing AST include path
+#endif
+#endif
+
+#ifndef MG_INJECTED_NAMESPACE_NAME
+#ifdef MG_CLANG_TIDY_CHECK
+// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define MG_INJECTED_NAMESPACE_NAME memgraph::query::v2
+#else
+#error Missing AST namespace
+#endif
+#endif
+
+#include MG_AST_INCLUDE_PATH
+
+namespace memgraph::expr {
+using namespace MG_INJECTED_NAMESPACE_NAME;  // NOLINT(google-build-using-namespace)
+}  // namespace memgraph::expr

src/expr/ast/ast_visitor.hpp

@@ -13,7 +13,7 @@
 
 #include "utils/visitor.hpp"
 
-namespace memgraph::query::v2 {
+namespace MG_INJECTED_NAMESPACE_NAME {
 
 // Forward declares for Tree visitors.
 class CypherQuery;
@@ -94,8 +94,9 @@ class StreamQuery;
 class SettingQuery;
 class VersionQuery;
 class Foreach;
+class SchemaQuery;
 
-using TreeCompositeVisitor = utils::CompositeVisitor<
+using TreeCompositeVisitor = memgraph::utils::CompositeVisitor<
     SingleQuery, CypherUnion, NamedExpression, OrOperator, XorOperator, AndOperator, NotOperator, AdditionOperator,
     SubtractionOperator, MultiplicationOperator, DivisionOperator, ModOperator, NotEqualOperator, EqualOperator,
     LessOperator, GreaterOperator, LessEqualOperator, GreaterEqualOperator, InListOperator, SubscriptOperator,
@@ -104,7 +105,7 @@ using TreeCompositeVisitor = utils::CompositeVisitor<
     Create, Match, Return, With, Pattern, NodeAtom, EdgeAtom, Delete, Where, SetProperty, SetProperties, SetLabels,
     RemoveProperty, RemoveLabels, Merge, Unwind, RegexMatch, LoadCsv, Foreach>;
 
-using TreeLeafVisitor = utils::LeafVisitor<Identifier, PrimitiveLiteral, ParameterLookup>;
+using TreeLeafVisitor = memgraph::utils::LeafVisitor<Identifier, PrimitiveLiteral, ParameterLookup>;
 
 class HierarchicalTreeVisitor : public TreeCompositeVisitor, public TreeLeafVisitor {
  public:
@@ -116,7 +117,7 @@ class HierarchicalTreeVisitor : public TreeCompositeVisitor, public TreeLeafVisi
 
 template <class TResult>
 class ExpressionVisitor
-    : public utils::Visitor<
+    : public memgraph::utils::Visitor<
           TResult, NamedExpression, OrOperator, XorOperator, AndOperator, NotOperator, AdditionOperator,
           SubtractionOperator, MultiplicationOperator, DivisionOperator, ModOperator, NotEqualOperator, EqualOperator,
           LessOperator, GreaterOperator, LessEqualOperator, GreaterEqualOperator, InListOperator, SubscriptOperator,
@@ -126,8 +127,9 @@ class ExpressionVisitor
 
 template <class TResult>
 class QueryVisitor
-    : public utils::Visitor<TResult, CypherQuery, ExplainQuery, ProfileQuery, IndexQuery, AuthQuery, InfoQuery,
-                            ConstraintQuery, DumpQuery, ReplicationQuery, LockPathQuery, FreeMemoryQuery, TriggerQuery,
-                            IsolationLevelQuery, CreateSnapshotQuery, StreamQuery, SettingQuery, VersionQuery> {};
+    : public memgraph::utils::Visitor<TResult, CypherQuery, ExplainQuery, ProfileQuery, IndexQuery, AuthQuery,
+                                      InfoQuery, ConstraintQuery, DumpQuery, ReplicationQuery, LockPathQuery,
+                                      FreeMemoryQuery, TriggerQuery, IsolationLevelQuery, CreateSnapshotQuery,
+                                      StreamQuery, SettingQuery, VersionQuery, SchemaQuery> {};
 
-}  // namespace memgraph::query::v2
+}  // namespace MG_INJECTED_NAMESPACE_NAME

src/expr/ast/pretty_print.hpp

@@ -0,0 +1,271 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <iostream>
+#include <type_traits>
+
+#include "expr/ast.hpp"
+#include "expr/typed_value.hpp"
+#include "utils/algorithm.hpp"
+#include "utils/logging.hpp"
+#include "utils/string.hpp"
+
+namespace memgraph::expr {
+namespace detail {
+template <typename T>
+void PrintObject(std::ostream *out, const T &arg) {
+  static_assert(!std::is_convertible<T, Expression *>::value,
+                "This overload shouldn't be called with pointers convertible "
+                "to Expression *. This means your other PrintObject overloads aren't "
+                "being called for certain AST nodes when they should (or perhaps such "
+                "overloads don't exist yet).");
+  *out << arg;
+}
+
+inline void PrintObject(std::ostream *out, const std::string &str) { *out << utils::Escape(str); }
+
+inline void PrintObject(std::ostream *out, Aggregation::Op op) { *out << Aggregation::OpToString(op); }
+
+inline void PrintObject(std::ostream *out, Expression *expr);
+
+inline void PrintObject(std::ostream *out, Identifier *expr) { PrintObject(out, static_cast<Expression *>(expr)); }
+
+template <typename T>
+void PrintObject(std::ostream *out, const std::vector<T> &vec) {
+  *out << "[";
+  utils::PrintIterable(*out, vec, ", ", [](auto &stream, const auto &item) { PrintObject(&stream, item); });
+  *out << "]";
+}
+
+template <typename T>
+void PrintObject(std::ostream *out, const std::vector<T, utils::Allocator<T>> &vec) {
+  *out << "[";
+  utils::PrintIterable(*out, vec, ", ", [](auto &stream, const auto &item) { PrintObject(&stream, item); });
+  *out << "]";
+}
+
+template <typename K, typename V>
+void PrintObject(std::ostream *out, const std::map<K, V> &map) {
+  *out << "{";
+  utils::PrintIterable(*out, map, ", ", [](auto &stream, const auto &item) {
+    PrintObject(&stream, item.first);
+    stream << ": ";
+    PrintObject(&stream, item.second);
+  });
+  *out << "}";
+}
+
+template <typename T>
+void PrintObject(std::ostream *out, const utils::pmr::map<utils::pmr::string, T> &map) {
+  *out << "{";
+  utils::PrintIterable(*out, map, ", ", [](auto &stream, const auto &item) {
+    PrintObject(&stream, item.first);
+    stream << ": ";
+    PrintObject(&stream, item.second);
+  });
+  *out << "}";
+}
+
+template <typename T1, typename T2, typename T3>
+inline void PrintObject(std::ostream *out, const TypedValueT<T1, T2, T3> &value) {
+  using TypedValue = TypedValueT<T1, T2, T3>;
+  switch (value.type()) {
+    case TypedValue::Type::Null:
+      *out << "null";
+      break;
+    case TypedValue::Type::String:
+      PrintObject(out, value.ValueString());
+      break;
+    case TypedValue::Type::Bool:
+      *out << (value.ValueBool() ? "true" : "false");
+      break;
+    case TypedValue::Type::Int:
+      PrintObject(out, value.ValueInt());
+      break;
+    case TypedValue::Type::Double:
+      PrintObject(out, value.ValueDouble());
+      break;
+    case TypedValue::Type::List:
+      PrintObject(out, value.ValueList());
+      break;
+    case TypedValue::Type::Map:
+      PrintObject(out, value.ValueMap());
+      break;
+    case TypedValue::Type::Date:
+      PrintObject(out, value.ValueDate());
+      break;
+    case TypedValue::Type::Duration:
+      PrintObject(out, value.ValueDuration());
+      break;
+    case TypedValue::Type::LocalTime:
+      PrintObject(out, value.ValueLocalTime());
+      break;
+    case TypedValue::Type::LocalDateTime:
+      PrintObject(out, value.ValueLocalDateTime());
+      break;
+    default:
+      MG_ASSERT(false, "PrintObject(std::ostream *out, const TypedValue &value) should not reach here");
+  }
+}
+
+template <typename T>
+void PrintOperatorArgs(std::ostream *out, const T &arg) {
+  *out << " ";
+  PrintObject(out, arg);
+  *out << ")";
+}
+
+template <typename T, typename... Ts>
+void PrintOperatorArgs(std::ostream *out, const T &arg, const Ts &...args) {
+  *out << " ";
+  PrintObject(out, arg);
+  PrintOperatorArgs(out, args...);
+}
+
+template <typename... Ts>
+void PrintOperator(std::ostream *out, const std::string &name, const Ts &...args) {
+  *out << "(" << name;
+  PrintOperatorArgs(out, args...);
+}
+}  // namespace detail
+
+class ExpressionPrettyPrinter : public ExpressionVisitor<void> {
+ public:
+  explicit ExpressionPrettyPrinter(std::ostream *out) : out_(out) {}
+
+  // Unary operators
+  // NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define UNARY_OPERATOR_VISIT(OP_NODE, OP_STR)      \
+  /* NOLINTNEXTLINE(bugprone-macro-parentheses) */ \
+  void Visit(OP_NODE &op) override { detail::PrintOperator(out_, OP_STR, op.expression_); }
+
+  UNARY_OPERATOR_VISIT(NotOperator, "Not");
+  UNARY_OPERATOR_VISIT(UnaryPlusOperator, "+");
+  UNARY_OPERATOR_VISIT(UnaryMinusOperator, "-");
+  UNARY_OPERATOR_VISIT(IsNullOperator, "IsNull");
+
+#undef UNARY_OPERATOR_VISIT
+
+  // Binary operators
+// NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define BINARY_OPERATOR_VISIT(OP_NODE, OP_STR)     \
+  /* NOLINTNEXTLINE(bugprone-macro-parentheses) */ \
+  void Visit(OP_NODE &op) override { detail::PrintOperator(out_, OP_STR, op.expression1_, op.expression2_); }
+
+  BINARY_OPERATOR_VISIT(OrOperator, "Or");
+  BINARY_OPERATOR_VISIT(XorOperator, "Xor");
+  BINARY_OPERATOR_VISIT(AndOperator, "And");
+  BINARY_OPERATOR_VISIT(AdditionOperator, "+");
+  BINARY_OPERATOR_VISIT(SubtractionOperator, "-");
+  BINARY_OPERATOR_VISIT(MultiplicationOperator, "*");
+  BINARY_OPERATOR_VISIT(DivisionOperator, "/");
+  BINARY_OPERATOR_VISIT(ModOperator, "%");
+  BINARY_OPERATOR_VISIT(NotEqualOperator, "!=");
+  BINARY_OPERATOR_VISIT(EqualOperator, "==");
+  BINARY_OPERATOR_VISIT(LessOperator, "<");
+  BINARY_OPERATOR_VISIT(GreaterOperator, ">");
+  BINARY_OPERATOR_VISIT(LessEqualOperator, "<=");
+  BINARY_OPERATOR_VISIT(GreaterEqualOperator, ">=");
+  BINARY_OPERATOR_VISIT(InListOperator, "In");
+  BINARY_OPERATOR_VISIT(SubscriptOperator, "Subscript");
+
+#undef BINARY_OPERATOR_VISIT
+
+  // Other
+  void Visit(ListSlicingOperator &op) override {
+    detail::PrintOperator(out_, "ListSlicing", op.list_, op.lower_bound_, op.upper_bound_);
+  }
+
+  void Visit(IfOperator &op) override {
+    detail::PrintOperator(out_, "If", op.condition_, op.then_expression_, op.else_expression_);
+  }
+
+  void Visit(ListLiteral &op) override { detail::PrintOperator(out_, "ListLiteral", op.elements_); }
+
+  void Visit(MapLiteral &op) override {
+    std::map<std::string, Expression *> map;
+    for (const auto &kv : op.elements_) {
+      map[kv.first.name] = kv.second;
+    }
+    detail::PrintObject(out_, map);
+  }
+
+  void Visit(LabelsTest &op) override { detail::PrintOperator(out_, "LabelsTest", op.expression_); }
+
+  void Visit(Aggregation &op) override { detail::PrintOperator(out_, "Aggregation", op.op_); }
+
+  void Visit(Function &op) override { detail::PrintOperator(out_, "Function", op.function_name_, op.arguments_); }
+
+  void Visit(Reduce &op) override {
+    detail::PrintOperator(out_, "Reduce", op.accumulator_, op.initializer_, op.identifier_, op.list_, op.expression_);
+  }
+
+  void Visit(Coalesce &op) override { detail::PrintOperator(out_, "Coalesce", op.expressions_); }
+
+  void Visit(Extract &op) override { detail::PrintOperator(out_, "Extract", op.identifier_, op.list_, op.expression_); }
+
+  void Visit(All &op) override {
+    detail::PrintOperator(out_, "All", op.identifier_, op.list_expression_, op.where_->expression_);
+  }
+
+  void Visit(Single &op) override {
+    detail::PrintOperator(out_, "Single", op.identifier_, op.list_expression_, op.where_->expression_);
+  }
+
+  void Visit(Any &op) override {
+    detail::PrintOperator(out_, "Any", op.identifier_, op.list_expression_, op.where_->expression_);
+  }
+
+  void Visit(None &op) override {
+    detail::PrintOperator(out_, "None", op.identifier_, op.list_expression_, op.where_->expression_);
+  }
+
+  void Visit(Identifier &op) override { detail::PrintOperator(out_, "Identifier", op.name_); }
+
+  void Visit(PrimitiveLiteral &op) override { detail::PrintObject(out_, op.value_); }
+
+  void Visit(PropertyLookup &op) override {
+    detail::PrintOperator(out_, "PropertyLookup", op.expression_, op.property_.name);
+  }
+
+  void Visit(ParameterLookup &op) override { detail::PrintOperator(out_, "ParameterLookup", op.token_position_); }
+
+  void Visit(NamedExpression &op) override { detail::PrintOperator(out_, "NamedExpression", op.name_, op.expression_); }
+
+  void Visit(RegexMatch &op) override { detail::PrintOperator(out_, "=~", op.string_expr_, op.regex_); }
+
+ private:
+  std::ostream *out_;
+};
+
+namespace detail {
+inline void PrintObject(std::ostream *out, Expression *expr) {
+  if (expr) {
+    ExpressionPrettyPrinter printer{out};
+    expr->Accept(printer);
+  } else {
+    *out << "<null>";
+  }
+}
+}  // namespace detail
+
+inline void PrintExpression(Expression *expr, std::ostream *out) {
+  ExpressionPrettyPrinter printer{out};
+  expr->Accept(printer);
+}
+
+inline void PrintExpression(NamedExpression *expr, std::ostream *out) {
+  ExpressionPrettyPrinter printer{out};
+  expr->Accept(printer);
+}
+}  // namespace memgraph::expr

src/expr/exceptions.hpp

@@ -0,0 +1,52 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "utils/exceptions.hpp"
+
+namespace memgraph::expr {
+
+class SyntaxException : public utils::BasicException {
+ public:
+  using utils::BasicException::BasicException;
+  SyntaxException() : SyntaxException("") {}
+};
+
+class SemanticException : public utils::BasicException {
+ public:
+  using utils::BasicException::BasicException;
+  SemanticException() : BasicException("") {}
+};
+
+class ExpressionRuntimeException : public utils::BasicException {
+ public:
+  using utils::BasicException::BasicException;
+};
+
+class RedeclareVariableError : public SemanticException {
+ public:
+  explicit RedeclareVariableError(const std::string &name) : SemanticException("Redeclaring variable: " + name + ".") {}
+};
+
+class UnboundVariableError : public SemanticException {
+ public:
+  explicit UnboundVariableError(const std::string &name) : SemanticException("Unbound variable: " + name + ".") {}
+};
+
+class TypeMismatchError : public SemanticException {
+ public:
+  TypeMismatchError(const std::string &name, const std::string &datum, const std::string &expected)
+      : SemanticException(fmt::format("Type mismatch: {} already defined as {}, expected {}.", name, datum, expected)) {
+  }
+};
+
+}  // namespace memgraph::expr

src/expr/interpret/eval.hpp

@@ -17,24 +17,26 @@
 #include <map>
 #include <optional>
 #include <regex>
+#include <type_traits>
 #include <vector>
 
-#include "query/v2/common.hpp"
-#include "query/v2/context.hpp"
-#include "query/v2/db_accessor.hpp"
-#include "query/v2/exceptions.hpp"
-#include "query/v2/frontend/ast/ast.hpp"
-#include "query/v2/frontend/semantic/symbol_table.hpp"
-#include "query/v2/interpret/frame.hpp"
-#include "query/v2/typed_value.hpp"
+#include "expr/ast.hpp"
+#include "expr/exceptions.hpp"
+#include "expr/interpret/frame.hpp"
+#include "expr/semantic/symbol_table.hpp"
 #include "utils/exceptions.hpp"
 
-namespace memgraph::query::v2 {
+namespace memgraph::expr {
 
+struct StorageTag {};
+struct QueryEngineTag {};
+
+template <typename TypedValue, typename EvaluationContext, typename DbAccessor, typename StorageView, typename LabelId,
+          typename PropertyValue, typename ConvFunctor, typename Error, typename Tag = StorageTag>
 class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
  public:
-  ExpressionEvaluator(Frame *frame, const SymbolTable &symbol_table, const EvaluationContext &ctx, DbAccessor *dba,
-                      storage::v3::View view)
+  ExpressionEvaluator(Frame<TypedValue> *frame, const SymbolTable &symbol_table, const EvaluationContext &ctx,
+                      DbAccessor *dba, StorageView view)
       : frame_(frame), symbol_table_(&symbol_table), ctx_(&ctx), dba_(dba), view_(view) {}
 
   using ExpressionVisitor<TypedValue>::Visit;
@@ -52,25 +54,29 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     return TypedValue(frame_->at(symbol_table_->at(ident)), ctx_->memory);
   }
 
-#define BINARY_OPERATOR_VISITOR(OP_NODE, CPP_OP, CYPHER_OP)                                                    \
-  TypedValue Visit(OP_NODE &op) override {                                                                     \
-    auto val1 = op.expression1_->Accept(*this);                                                                \
-    auto val2 = op.expression2_->Accept(*this);                                                                \
-    try {                                                                                                      \
-      return val1 CPP_OP val2;                                                                                 \
-    } catch (const TypedValueException &) {                                                                    \
-      throw QueryRuntimeException("Invalid types: {} and {} for '{}'.", val1.type(), val2.type(), #CYPHER_OP); \
-    }                                                                                                          \
+  // NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define BINARY_OPERATOR_VISITOR(OP_NODE, CPP_OP, CYPHER_OP)                                                         \
+  /* NOLINTNEXTLINE(bugprone-macro-parentheses) */                                                                  \
+  TypedValue Visit(OP_NODE &op) override {                                                                          \
+    auto val1 = op.expression1_->Accept(*this);                                                                     \
+    auto val2 = op.expression2_->Accept(*this);                                                                     \
+    try {                                                                                                           \
+      return val1 CPP_OP val2;                                                                                      \
+    } catch (const TypedValueException &) {                                                                         \
+      throw ExpressionRuntimeException("Invalid types: {} and {} for '{}'.", val1.type(), val2.type(), #CYPHER_OP); \
+    }                                                                                                               \
   }
 
-#define UNARY_OPERATOR_VISITOR(OP_NODE, CPP_OP, CYPHER_OP)                              \
-  TypedValue Visit(OP_NODE &op) override {                                              \
-    auto val = op.expression_->Accept(*this);                                           \
-    try {                                                                               \
-      return CPP_OP val;                                                                \
-    } catch (const TypedValueException &) {                                             \
-      throw QueryRuntimeException("Invalid type {} for '{}'.", val.type(), #CYPHER_OP); \
-    }                                                                                   \
+  // NOLINTNEXTLINE(cppcoreguidelines-macro-usage)
+#define UNARY_OPERATOR_VISITOR(OP_NODE, CPP_OP, CYPHER_OP)                                   \
+  /* NOLINTNEXTLINE(bugprone-macro-parentheses) */                                           \
+  TypedValue Visit(OP_NODE &op) override {                                                   \
+    auto val = op.expression_->Accept(*this);                                                \
+    try {                                                                                    \
+      return CPP_OP val;                                                                     \
+    } catch (const TypedValueException &) {                                                  \
+      throw ExpressionRuntimeException("Invalid type {} for '{}'.", val.type(), #CYPHER_OP); \
+    }                                                                                        \
   }
 
   BINARY_OPERATOR_VISITOR(OrOperator, ||, OR);
@@ -104,18 +110,18 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     try {
       return value1 && value2;
     } catch (const TypedValueException &) {
-      throw QueryRuntimeException("Invalid types: {} and {} for AND.", value1.type(), value2.type());
+      throw ExpressionRuntimeException("Invalid types: {} and {} for AND.", value1.type(), value2.type());
     }
   }
 
   TypedValue Visit(IfOperator &if_operator) override {
     auto condition = if_operator.condition_->Accept(*this);
     if (condition.IsNull()) {
-      return if_operator.then_expression_->Accept(*this);
+      return if_operator.else_expression_->Accept(*this);
     }
     if (condition.type() != TypedValue::Type::Bool) {
       // At the moment IfOperator is used only in CASE construct.
-      throw QueryRuntimeException("CASE expected boolean expression, got {}.", condition.type());
+      throw ExpressionRuntimeException("CASE expected boolean expression, got {}.", condition.type());
     }
     if (condition.ValueBool()) {
       return if_operator.then_expression_->Accept(*this);
@@ -132,7 +138,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     // Exceptions have higher priority than returning nulls when list expression
     // is not null.
     if (_list.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("IN expected a list, got {}.", _list.type());
+      throw ExpressionRuntimeException("IN expected a list, got {}.", _list.type());
     }
     const auto &list = _list.ValueList();
 
@@ -162,13 +168,14 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     auto lhs = list_indexing.expression1_->Accept(*this);
     auto index = list_indexing.expression2_->Accept(*this);
     if (!lhs.IsList() && !lhs.IsMap() && !lhs.IsVertex() && !lhs.IsEdge() && !lhs.IsNull())
-      throw QueryRuntimeException(
+      throw ExpressionRuntimeException(
           "Expected a list, a map, a node or an edge to index with '[]', got "
           "{}.",
           lhs.type());
     if (lhs.IsNull() || index.IsNull()) return TypedValue(ctx_->memory);
     if (lhs.IsList()) {
-      if (!index.IsInt()) throw QueryRuntimeException("Expected an integer as a list index, got {}.", index.type());
+      if (!index.IsInt())
+        throw ExpressionRuntimeException("Expected an integer as a list index, got {}.", index.type());
       auto index_int = index.ValueInt();
       // NOTE: Take non-const reference to list, so that we can move out the
       // indexed element as the result.
@@ -183,7 +190,8 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     }
 
     if (lhs.IsMap()) {
-      if (!index.IsString()) throw QueryRuntimeException("Expected a string as a map index, got {}.", index.type());
+      if (!index.IsString())
+        throw ExpressionRuntimeException("Expected a string as a map index, got {}.", index.type());
       // NOTE: Take non-const reference to map, so that we can move out the
       // looked-up element as the result.
       auto &map = lhs.ValueMap();
@@ -195,12 +203,14 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     }
 
     if (lhs.IsVertex()) {
-      if (!index.IsString()) throw QueryRuntimeException("Expected a string as a property name, got {}.", index.type());
+      if (!index.IsString())
+        throw ExpressionRuntimeException("Expected a string as a property name, got {}.", index.type());
       return TypedValue(GetProperty(lhs.ValueVertex(), index.ValueString()), ctx_->memory);
     }
 
     if (lhs.IsEdge()) {
-      if (!index.IsString()) throw QueryRuntimeException("Expected a string as a property name, got {}.", index.type());
+      if (!index.IsString())
+        throw ExpressionRuntimeException("Expected a string as a property name, got {}.", index.type());
       return TypedValue(GetProperty(lhs.ValueEdge(), index.ValueString()), ctx_->memory);
     }
 
@@ -218,7 +228,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         if (bound.type() == TypedValue::Type::Null) {
           is_null = true;
         } else if (bound.type() != TypedValue::Type::Int) {
-          throw QueryRuntimeException("Expected an integer for a bound in list slicing, got {}.", bound.type());
+          throw ExpressionRuntimeException("Expected an integer for a bound in list slicing, got {}.", bound.type());
         }
         return bound;
       }
@@ -231,7 +241,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     if (_list.type() == TypedValue::Type::Null) {
       is_null = true;
     } else if (_list.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("Expected a list to slice, got {}.", _list.type());
+      throw ExpressionRuntimeException("Expected a list to slice, got {}.", _list.type());
     }
 
     if (is_null) {
@@ -247,9 +257,10 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     auto lower_bound = normalise_bound(_lower_bound.ValueInt());
     auto upper_bound = normalise_bound(_upper_bound.ValueInt());
     if (upper_bound <= lower_bound) {
-      return TypedValue(TypedValue::TVector(ctx_->memory), ctx_->memory);
+      return TypedValue(typename TypedValue::TVector(ctx_->memory), ctx_->memory);
     }
-    return TypedValue(TypedValue::TVector(list.begin() + lower_bound, list.begin() + upper_bound, ctx_->memory));
+    return TypedValue(
+        typename TypedValue::TVector(list.begin() + lower_bound, list.begin() + upper_bound, ctx_->memory));
   }
 
   TypedValue Visit(IsNullOperator &is_null) override {
@@ -317,9 +328,9 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       case TypedValue::Type::Null:
         return TypedValue(ctx_->memory);
       case TypedValue::Type::Vertex:
-        return TypedValue(GetProperty(expression_result.ValueVertex(), property_lookup.property_), ctx_->memory);
+        return GetProperty(expression_result.ValueVertex(), property_lookup.property_);
       case TypedValue::Type::Edge:
-        return TypedValue(GetProperty(expression_result.ValueEdge(), property_lookup.property_), ctx_->memory);
+        return GetProperty(expression_result.ValueEdge(), property_lookup.property_);
       case TypedValue::Type::Map: {
         // NOTE: Take non-const reference to map, so that we can move out the
         // looked-up element as the result.
@@ -336,7 +347,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         if (auto dur_field = maybe_duration(dur, prop_name); dur_field) {
           return std::move(*dur_field);
         }
-        throw QueryRuntimeException("Invalid property name {} for Duration", prop_name);
+        throw ExpressionRuntimeException("Invalid property name {} for Duration", prop_name);
       }
       case TypedValue::Type::Date: {
         const auto &prop_name = property_lookup.property_.name;
@@ -344,7 +355,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         if (auto date_field = maybe_date(date, prop_name); date_field) {
           return std::move(*date_field);
         }
-        throw QueryRuntimeException("Invalid property name {} for Date", prop_name);
+        throw ExpressionRuntimeException("Invalid property name {} for Date", prop_name);
       }
       case TypedValue::Type::LocalTime: {
         const auto &prop_name = property_lookup.property_.name;
@@ -352,7 +363,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         if (auto lt_field = maybe_local_time(lt, prop_name); lt_field) {
           return std::move(*lt_field);
         }
-        throw QueryRuntimeException("Invalid property name {} for LocalTime", prop_name);
+        throw ExpressionRuntimeException("Invalid property name {} for LocalTime", prop_name);
       }
       case TypedValue::Type::LocalDateTime: {
         const auto &prop_name = property_lookup.property_.name;
@@ -363,13 +374,50 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         if (auto lt_field = maybe_local_time(ldt.local_time, prop_name); lt_field) {
           return std::move(*lt_field);
         }
-        throw QueryRuntimeException("Invalid property name {} for LocalDateTime", prop_name);
+        throw ExpressionRuntimeException("Invalid property name {} for LocalDateTime", prop_name);
       }
       default:
-        throw QueryRuntimeException("Only nodes, edges, maps and temporal types have properties to be looked-up.");
+        throw ExpressionRuntimeException("Only nodes, edges, maps and temporal types have properties to be looked-up.");
     }
   }
 
+  template <typename VertexAccessor, typename TTag = Tag,
+            typename TReturnType = std::enable_if_t<std::is_same_v<TTag, StorageTag>, bool>>
+  TReturnType HasLabelImpl(const VertexAccessor &vertex, const LabelIx &label, StorageTag /*tag*/) {
+    auto has_label = vertex.HasLabel(view_, GetLabel(label));
+    if (has_label.HasError() && has_label.GetError() == Error::NONEXISTENT_OBJECT) {
+      // This is a very nasty and temporary hack in order to make MERGE
+      // work. The old storage had the following logic when returning an
+      // `OLD` view: `return old ? old : new`. That means that if the
+      // `OLD` view didn't exist, it returned the NEW view. With this hack
+      // we simulate that behavior.
+      // TODO (mferencevic, teon.banek): Remove once MERGE is
+      // reimplemented.
+      has_label = vertex.HasLabel(StorageView::NEW, GetLabel(label));
+    }
+    if (has_label.HasError()) {
+      switch (has_label.GetError()) {
+        case Error::DELETED_OBJECT:
+          throw ExpressionRuntimeException("Trying to access labels on a deleted node.");
+        case Error::NONEXISTENT_OBJECT:
+          throw ExpressionRuntimeException("Trying to access labels from a node that doesn't exist.");
+        case Error::SERIALIZATION_ERROR:
+        case Error::VERTEX_HAS_EDGES:
+        case Error::PROPERTIES_DISABLED:
+          throw ExpressionRuntimeException("Unexpected error when accessing labels.");
+      }
+    }
+    return *has_label;
+  }
+
+  template <typename VertexAccessor, typename TTag = Tag,
+            typename TReturnType = std::enable_if_t<std::is_same_v<TTag, QueryEngineTag>, bool>>
+  TReturnType HasLabelImpl(const VertexAccessor &vertex, const LabelIx &label_ix, QueryEngineTag /*tag*/) {
+    auto label = typename VertexAccessor::Label{LabelId::FromUint(label_ix.ix)};
+    auto has_label = vertex.HasLabel(label);
+    return !has_label;
+  }
+
   TypedValue Visit(LabelsTest &labels_test) override {
     auto expression_result = labels_test.expression_->Accept(*this);
     switch (expression_result.type()) {
@@ -377,38 +425,15 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
         return TypedValue(ctx_->memory);
       case TypedValue::Type::Vertex: {
         const auto &vertex = expression_result.ValueVertex();
-        for (const auto &label : labels_test.labels_) {
-          auto has_label = vertex.HasLabel(view_, GetLabel(label));
-          if (has_label.HasError() && has_label.GetError() == storage::v3::Error::NONEXISTENT_OBJECT) {
-            // This is a very nasty and temporary hack in order to make MERGE
-            // work. The old storage had the following logic when returning an
-            // `OLD` view: `return old ? old : new`. That means that if the
-            // `OLD` view didn't exist, it returned the NEW view. With this hack
-            // we simulate that behavior.
-            // TODO (mferencevic, teon.banek): Remove once MERGE is
-            // reimplemented.
-            has_label = vertex.HasLabel(storage::v3::View::NEW, GetLabel(label));
-          }
-          if (has_label.HasError()) {
-            switch (has_label.GetError()) {
-              case storage::v3::Error::DELETED_OBJECT:
-                throw QueryRuntimeException("Trying to access labels on a deleted node.");
-              case storage::v3::Error::NONEXISTENT_OBJECT:
-                throw query::v2::QueryRuntimeException("Trying to access labels from a node that doesn't exist.");
-              case storage::v3::Error::SERIALIZATION_ERROR:
-              case storage::v3::Error::VERTEX_HAS_EDGES:
-              case storage::v3::Error::PROPERTIES_DISABLED:
-                throw QueryRuntimeException("Unexpected error when accessing labels.");
-            }
-          }
-          if (!*has_label) {
-            return TypedValue(false, ctx_->memory);
-          }
+        if (std::ranges::all_of(labels_test.labels_, [&vertex, this](const auto label_test) {
+              return this->HasLabelImpl(vertex, label_test, Tag{});
+            })) {
+          return TypedValue(true, ctx_->memory);
         }
-        return TypedValue(true, ctx_->memory);
+        return TypedValue(false, ctx_->memory);
       }
       default:
-        throw QueryRuntimeException("Only nodes have labels.");
+        throw ExpressionRuntimeException("Only nodes have labels.");
     }
   }
 
@@ -419,14 +444,14 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
   }
 
   TypedValue Visit(ListLiteral &literal) override {
-    TypedValue::TVector result(ctx_->memory);
+    typename TypedValue::TVector result(ctx_->memory);
     result.reserve(literal.elements_.size());
     for (const auto &expression : literal.elements_) result.emplace_back(expression->Accept(*this));
     return TypedValue(result, ctx_->memory);
   }
 
   TypedValue Visit(MapLiteral &literal) override {
-    TypedValue::TMap result(ctx_->memory);
+    typename TypedValue::TMap result(ctx_->memory);
     for (const auto &pair : literal.elements_) result.emplace(pair.first.name, pair.second->Accept(*this));
     return TypedValue(result, ctx_->memory);
   }
@@ -439,7 +464,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     auto &exprs = coalesce.expressions_;
 
     if (exprs.size() == 0) {
-      throw QueryRuntimeException("'coalesce' requires at least one argument.");
+      throw ExpressionRuntimeException("'coalesce' requires at least one argument.");
     }
 
     for (int64_t i = 0; i < exprs.size(); ++i) {
@@ -466,7 +491,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       MG_ASSERT(res.GetMemoryResource() == ctx_->memory);
       return res;
     } else {
-      TypedValue::TVector arguments(ctx_->memory);
+      typename TypedValue::TVector arguments(ctx_->memory);
       arguments.reserve(function.arguments_.size());
       for (const auto &argument : function.arguments_) {
         arguments.emplace_back(argument->Accept(*this));
@@ -483,7 +508,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("REDUCE expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("REDUCE expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &element_symbol = symbol_table_->at(*reduce.identifier_);
@@ -503,11 +528,11 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("EXTRACT expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("EXTRACT expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &element_symbol = symbol_table_->at(*extract.identifier_);
-    TypedValue::TVector result(ctx_->memory);
+    typename TypedValue::TVector result(ctx_->memory);
     result.reserve(list.size());
     for (const auto &element : list) {
       if (element.IsNull()) {
@@ -526,7 +551,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("ALL expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("ALL expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &symbol = symbol_table_->at(*all.identifier_);
@@ -536,7 +561,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       frame_->at(symbol) = element;
       auto result = all.where_->expression_->Accept(*this);
       if (!result.IsNull() && result.type() != TypedValue::Type::Bool) {
-        throw QueryRuntimeException("Predicate of ALL must evaluate to boolean, got {}.", result.type());
+        throw ExpressionRuntimeException("Predicate of ALL must evaluate to boolean, got {}.", result.type());
       }
       if (!result.IsNull()) {
         has_value = true;
@@ -563,7 +588,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("SINGLE expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("SINGLE expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &symbol = symbol_table_->at(*single.identifier_);
@@ -573,7 +598,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       frame_->at(symbol) = element;
       auto result = single.where_->expression_->Accept(*this);
       if (!result.IsNull() && result.type() != TypedValue::Type::Bool) {
-        throw QueryRuntimeException("Predicate of SINGLE must evaluate to boolean, got {}.", result.type());
+        throw ExpressionRuntimeException("Predicate of SINGLE must evaluate to boolean, got {}.", result.type());
       }
       if (result.type() == TypedValue::Type::Bool) {
         has_value = true;
@@ -601,7 +626,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("ANY expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("ANY expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &symbol = symbol_table_->at(*any.identifier_);
@@ -610,7 +635,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       frame_->at(symbol) = element;
       auto result = any.where_->expression_->Accept(*this);
       if (!result.IsNull() && result.type() != TypedValue::Type::Bool) {
-        throw QueryRuntimeException("Predicate of ANY must evaluate to boolean, got {}.", result.type());
+        throw ExpressionRuntimeException("Predicate of ANY must evaluate to boolean, got {}.", result.type());
       }
       if (!result.IsNull()) {
         has_value = true;
@@ -633,7 +658,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (list_value.type() != TypedValue::Type::List) {
-      throw QueryRuntimeException("NONE expected a list, got {}.", list_value.type());
+      throw ExpressionRuntimeException("NONE expected a list, got {}.", list_value.type());
     }
     const auto &list = list_value.ValueList();
     const auto &symbol = symbol_table_->at(*none.identifier_);
@@ -642,7 +667,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       frame_->at(symbol) = element;
       auto result = none.where_->expression_->Accept(*this);
       if (!result.IsNull() && result.type() != TypedValue::Type::Bool) {
-        throw QueryRuntimeException("Predicate of NONE must evaluate to boolean, got {}.", result.type());
+        throw ExpressionRuntimeException("Predicate of NONE must evaluate to boolean, got {}.", result.type());
       }
       if (!result.IsNull()) {
         has_value = true;
@@ -660,7 +685,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
   }
 
   TypedValue Visit(ParameterLookup &param_lookup) override {
-    return TypedValue(ctx_->parameters.AtTokenPosition(param_lookup.token_position_), ctx_->memory);
+    return TypedValue(conv_(ctx_->parameters.AtTokenPosition(param_lookup.token_position_)), ctx_->memory);
   }
 
   TypedValue Visit(RegexMatch &regex_match) override {
@@ -670,7 +695,7 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       return TypedValue(ctx_->memory);
     }
     if (regex_value.type() != TypedValue::Type::String) {
-      throw QueryRuntimeException("Regular expression must evaluate to a string, got {}.", regex_value.type());
+      throw ExpressionRuntimeException("Regular expression must evaluate to a string, got {}.", regex_value.type());
     }
     if (target_string_value.type() != TypedValue::Type::String) {
       // Instead of error, we return Null which makes it compatible in case we
@@ -683,42 +708,60 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
       std::regex regex(regex_value.ValueString());
       return TypedValue(std::regex_match(target_string, regex), ctx_->memory);
     } catch (const std::regex_error &e) {
-      throw QueryRuntimeException("Regex error in '{}': {}", regex_value.ValueString(), e.what());
+      throw ExpressionRuntimeException("Regex error in '{}': {}", regex_value.ValueString(), e.what());
     }
   }
 
  private:
-  template <class TRecordAccessor>
-  storage::v3::PropertyValue GetProperty(const TRecordAccessor &record_accessor, PropertyIx prop) {
+  template <class TRecordAccessor, class TTag = Tag,
+            class TReturnType = std::enable_if_t<std::is_same_v<TTag, QueryEngineTag>, TypedValue>>
+  TReturnType GetProperty(const TRecordAccessor &record_accessor, PropertyIx prop) {
+    auto maybe_prop = record_accessor.GetProperty(prop.name);
+    // Handler non existent property
+    return conv_(maybe_prop);
+  }
+
+  template <class TRecordAccessor, class TTag = Tag,
+            class TReturnType = std::enable_if_t<std::is_same_v<TTag, QueryEngineTag>, TypedValue>>
+  TReturnType GetProperty(const TRecordAccessor &record_accessor, const std::string_view name) {
+    auto maybe_prop = record_accessor.GetProperty(std::string(name));
+    // Handler non existent property
+    return conv_(maybe_prop);
+  }
+
+  template <class TRecordAccessor, class TTag = Tag,
+            class TReturnType = std::enable_if_t<std::is_same_v<TTag, StorageTag>, TypedValue>>
+  TypedValue GetProperty(const TRecordAccessor &record_accessor, PropertyIx prop) {
     auto maybe_prop = record_accessor.GetProperty(view_, ctx_->properties[prop.ix]);
-    if (maybe_prop.HasError() && maybe_prop.GetError() == storage::v3::Error::NONEXISTENT_OBJECT) {
+    if (maybe_prop.HasError() && maybe_prop.GetError() == Error::NONEXISTENT_OBJECT) {
       // This is a very nasty and temporary hack in order to make MERGE work.
       // The old storage had the following logic when returning an `OLD` view:
       // `return old ? old : new`. That means that if the `OLD` view didn't
       // exist, it returned the NEW view. With this hack we simulate that
       // behavior.
       // TODO (mferencevic, teon.banek): Remove once MERGE is reimplemented.
-      maybe_prop = record_accessor.GetProperty(storage::v3::View::NEW, ctx_->properties[prop.ix]);
+      maybe_prop = record_accessor.GetProperty(StorageView::NEW, ctx_->properties[prop.ix]);
     }
     if (maybe_prop.HasError()) {
       switch (maybe_prop.GetError()) {
-        case storage::v3::Error::DELETED_OBJECT:
-          throw QueryRuntimeException("Trying to get a property from a deleted object.");
-        case storage::v3::Error::NONEXISTENT_OBJECT:
-          throw query::v2::QueryRuntimeException("Trying to get a property from an object that doesn't exist.");
-        case storage::v3::Error::SERIALIZATION_ERROR:
-        case storage::v3::Error::VERTEX_HAS_EDGES:
-        case storage::v3::Error::PROPERTIES_DISABLED:
-          throw QueryRuntimeException("Unexpected error when getting a property.");
+        case Error::DELETED_OBJECT:
+          throw ExpressionRuntimeException("Trying to get a property from a deleted object.");
+        case Error::NONEXISTENT_OBJECT:
+          throw ExpressionRuntimeException("Trying to get a property from an object that doesn't exist.");
+        case Error::SERIALIZATION_ERROR:
+        case Error::VERTEX_HAS_EDGES:
+        case Error::PROPERTIES_DISABLED:
+          throw ExpressionRuntimeException("Unexpected error when getting a property.");
       }
     }
-    return *maybe_prop;
+    return conv_(*maybe_prop, ctx_->memory);
   }
 
-  template <class TRecordAccessor>
-  storage::v3::PropertyValue GetProperty(const TRecordAccessor &record_accessor, const std::string_view name) {
+  template <class TRecordAccessor, class TTag = Tag,
+            class TReturnType = std::enable_if_t<std::is_same_v<TTag, StorageTag>, TypedValue>>
+  TypedValue GetProperty(const TRecordAccessor &record_accessor, const std::string_view name) {
     auto maybe_prop = record_accessor.GetProperty(view_, dba_->NameToProperty(name));
-    if (maybe_prop.HasError() && maybe_prop.GetError() == storage::v3::Error::NONEXISTENT_OBJECT) {
+    if (maybe_prop.HasError() && maybe_prop.GetError() == Error::NONEXISTENT_OBJECT) {
       // This is a very nasty and temporary hack in order to make MERGE work.
       // The old storage had the following logic when returning an `OLD` view:
       // `return old ? old : new`. That means that if the `OLD` view didn't
@@ -729,36 +772,55 @@ class ExpressionEvaluator : public ExpressionVisitor<TypedValue> {
     }
     if (maybe_prop.HasError()) {
       switch (maybe_prop.GetError()) {
-        case storage::v3::Error::DELETED_OBJECT:
-          throw QueryRuntimeException("Trying to get a property from a deleted object.");
-        case storage::v3::Error::NONEXISTENT_OBJECT:
-          throw query::v2::QueryRuntimeException("Trying to get a property from an object that doesn't exist.");
-        case storage::v3::Error::SERIALIZATION_ERROR:
-        case storage::v3::Error::VERTEX_HAS_EDGES:
-        case storage::v3::Error::PROPERTIES_DISABLED:
-          throw QueryRuntimeException("Unexpected error when getting a property.");
+        case Error::DELETED_OBJECT:
+          throw ExpressionRuntimeException("Trying to get a property from a deleted object.");
+        case Error::NONEXISTENT_OBJECT:
+          throw ExpressionRuntimeException("Trying to get a property from an object that doesn't exist.");
+        case Error::SERIALIZATION_ERROR:
+        case Error::VERTEX_HAS_EDGES:
+        case Error::PROPERTIES_DISABLED:
+          throw ExpressionRuntimeException("Unexpected error when getting a property.");
       }
     }
-    return *maybe_prop;
+    return conv_(*maybe_prop, ctx_->memory);
   }
 
-  storage::v3::LabelId GetLabel(LabelIx label) { return ctx_->labels[label.ix]; }
+  LabelId GetLabel(LabelIx label) { return ctx_->labels[label.ix]; }
 
-  Frame *frame_;
+  Frame<TypedValue> *frame_;
   const SymbolTable *symbol_table_;
   const EvaluationContext *ctx_;
   DbAccessor *dba_;
   // which switching approach should be used when evaluating
-  storage::v3::View view_;
+  StorageView view_;
+  ConvFunctor conv_;
 };
 
 /// A helper function for evaluating an expression that's an int.
 ///
 /// @param what - Name of what's getting evaluated. Used for user feedback (via
 ///               exception) when the evaluated value is not an int.
-/// @throw QueryRuntimeException if expression doesn't evaluate to an int.
-int64_t EvaluateInt(ExpressionEvaluator *evaluator, Expression *expr, const std::string &what);
+/// @throw ExpressionRuntimeException if expression doesn't evaluate to an int.
+template <typename ExpressionEvaluator>
+int64_t EvaluateInt(ExpressionEvaluator *evaluator, Expression *expr, const std::string &what) {
+  TypedValue value = expr->Accept(*evaluator);
+  try {
+    return value.ValueInt();
+  } catch (TypedValueException &e) {
+    throw ExpressionRuntimeException(what + " must be an int");
+  }
+}
 
-std::optional<size_t> EvaluateMemoryLimit(ExpressionEvaluator *eval, Expression *memory_limit, size_t memory_scale);
+template <typename ExpressionEvaluator>
+std::optional<size_t> EvaluateMemoryLimit(ExpressionEvaluator *eval, Expression *memory_limit, size_t memory_scale) {
+  if (!memory_limit) return std::nullopt;
+  auto limit_value = memory_limit->Accept(*eval);
+  if (!limit_value.IsInt() || limit_value.ValueInt() <= 0)
+    throw ExpressionRuntimeException("Memory limit must be a non-negative integer.");
+  size_t limit = limit_value.ValueInt();
+  if (std::numeric_limits<size_t>::max() / memory_scale < limit)
+    throw ExpressionRuntimeException("Memory limit overflow.");
+  return limit * memory_scale;
+}
 
-}  // namespace memgraph::query::v2
+}  // namespace memgraph::expr

src/expr/interpret/frame.hpp

@@ -13,14 +13,14 @@
 
 #include <vector>
 
-#include "query/v2/frontend/semantic/symbol_table.hpp"
-#include "query/v2/typed_value.hpp"
+#include "expr/semantic/symbol_table.hpp"
 #include "utils/logging.hpp"
 #include "utils/memory.hpp"
 #include "utils/pmr/vector.hpp"
 
-namespace memgraph::query::v2 {
+namespace memgraph::expr {
 
+template <typename TypedValue>
 class Frame {
  public:
   /// Create a Frame of given size backed by a utils::NewDeleteResource()
@@ -42,4 +42,4 @@ class Frame {
   utils::pmr::vector<TypedValue> elems_;
 };
 
-}  // namespace memgraph::query::v2
+}  // namespace memgraph::expr

src/expr/parsing.cpp

@@ -9,18 +9,18 @@
 // by the Apache License, Version 2.0, included in the file
 // licenses/APL.txt.
 
-#include "query/v2/frontend/parsing.hpp"
+#include "expr/parsing.hpp"
 
 #include <cctype>
 #include <codecvt>
 #include <locale>
 #include <stdexcept>
 
-#include "query/v2/exceptions.hpp"
+#include "expr/exceptions.hpp"
 #include "utils/logging.hpp"
 #include "utils/string.hpp"
 
-namespace memgraph::query::v2::frontend {
+namespace memgraph::expr {
 
 int64_t ParseIntegerLiteral(const std::string &s) {
   try {
@@ -181,4 +181,4 @@ std::string ParseParameter(const std::string &s) {
   return out;
 }
 
-}  // namespace memgraph::query::v2::frontend
+}  // namespace memgraph::expr

src/expr/parsing.hpp

@@ -15,7 +15,7 @@
 #include <cstdint>
 #include <string>
 
-namespace memgraph::query::v2::frontend {
+namespace memgraph::expr {
 
 // These are the functions for parsing literals and parameter names from
 // opencypher query.
@@ -24,4 +24,4 @@ std::string ParseStringLiteral(const std::string &s);
 double ParseDoubleLiteral(const std::string &s);
 std::string ParseParameter(const std::string &s);
 
-}  // namespace memgraph::query::v2::frontend
+}  // namespace memgraph::expr

src/expr/semantic/symbol.lcp

@@ -18,8 +18,7 @@
 cpp<#
 
 (lcp:namespace memgraph)
-(lcp:namespace query)
-(lcp:namespace v2)
+(lcp:namespace expr)
 
 (lcp:define-class symbol ()
   ((name "std::string" :scope :public)
@@ -66,16 +65,15 @@ cpp<#
     cpp<#)
   (:serialize (:slk)))
 
-(lcp:pop-namespace) ;; v2
-(lcp:pop-namespace) ;; query
+(lcp:pop-namespace) ;; expr
 (lcp:pop-namespace) ;; memgraph
 
 #>cpp
 namespace std {
 
 template <>
-struct hash<memgraph::query::v2::Symbol> {
-  size_t operator()(const memgraph::query::v2::Symbol &symbol) const {
+struct hash<memgraph::expr::Symbol> {
+  size_t operator()(const memgraph::expr::Symbol &symbol) const {
     size_t prime = 265443599u;
     size_t hash = std::hash<int>{}(symbol.position());
     hash ^= prime * std::hash<std::string>{}(symbol.name());

src/expr/semantic/symbol_generator.hpp

@@ -0,0 +1,712 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+// Copyright 2017 Memgraph
+//
+// Created by Teon Banek on 11-03-2017
+
+#pragma once
+
+#include <algorithm>
+#include <optional>
+#include <ranges>
+#include <unordered_map>
+#include <unordered_set>
+#include <variant>
+#include <vector>
+
+#include "expr/ast.hpp"
+#include "expr/ast/ast_visitor.hpp"
+#include "expr/exceptions.hpp"
+#include "expr/semantic/symbol_table.hpp"
+
+namespace memgraph::expr {
+namespace detail {
+inline std::unordered_map<std::string, Identifier *> GeneratePredefinedIdentifierMap(
+    const std::vector<Identifier *> &predefined_identifiers) {
+  std::unordered_map<std::string, Identifier *> identifier_map;
+  for (const auto &identifier : predefined_identifiers) {
+    identifier_map.emplace(identifier->name_, identifier);
+  }
+
+  return identifier_map;
+}
+}  // namespace detail
+
+/// Visits the AST and generates symbols for variables.
+///
+/// During the process of symbol generation, simple semantic checks are
+/// performed. Such as, redeclaring a variable or conflicting expectations of
+/// variable types.
+class SymbolGenerator : public HierarchicalTreeVisitor {
+ public:
+  explicit SymbolGenerator(SymbolTable *symbol_table, const std::vector<Identifier *> &predefined_identifiers)
+      : symbol_table_(symbol_table),
+        predefined_identifiers_{detail::GeneratePredefinedIdentifierMap(predefined_identifiers)},
+        scopes_(1, Scope()) {}
+
+  using HierarchicalTreeVisitor::PostVisit;
+  using HierarchicalTreeVisitor::PreVisit;
+  using HierarchicalTreeVisitor::Visit;
+  using typename HierarchicalTreeVisitor::ReturnType;
+
+  // Query
+  bool PreVisit(SingleQuery & /*unused*/) override {
+    prev_return_names_ = curr_return_names_;
+    curr_return_names_.clear();
+    return true;
+  }
+
+  // Union
+  bool PreVisit(CypherUnion & /*unused*/) override {
+    scopes_.back() = Scope();
+    return true;
+  }
+
+  bool PostVisit(CypherUnion &cypher_union) override {
+    if (prev_return_names_ != curr_return_names_) {
+      throw SemanticException("All subqueries in an UNION must have the same column names.");
+    }
+
+    // create new symbols for the result of the union
+    for (const auto &name : curr_return_names_) {
+      auto symbol = CreateSymbol(name, false);
+      cypher_union.union_symbols_.push_back(symbol);
+    }
+
+    return true;
+  }
+
+  // Clauses
+  bool PreVisit(Create & /*unused*/) override {
+    scopes_.back().in_create = true;
+    return true;
+  }
+
+  bool PostVisit(Create & /*unused*/) override {
+    scopes_.back().in_create = false;
+    return true;
+  }
+
+  bool PreVisit(CallProcedure &call_proc) override {
+    for (auto *expr : call_proc.arguments_) {
+      expr->Accept(*this);
+    }
+    return false;
+  }
+
+  bool PostVisit(CallProcedure &call_proc) override {
+    for (auto *ident : call_proc.result_identifiers_) {
+      if (HasSymbolLocalScope(ident->name_)) {
+        throw RedeclareVariableError(ident->name_);
+      }
+      ident->MapTo(CreateSymbol(ident->name_, true));
+    }
+    return true;
+  }
+
+  bool PreVisit(LoadCsv & /*unused*/) override { return false; }
+
+  bool PostVisit(LoadCsv &load_csv) override {
+    if (HasSymbolLocalScope(load_csv.row_var_->name_)) {
+      throw RedeclareVariableError(load_csv.row_var_->name_);
+    }
+    load_csv.row_var_->MapTo(CreateSymbol(load_csv.row_var_->name_, true));
+    return true;
+  }
+
+  bool PreVisit(Return &ret) override {
+    auto &scope = scopes_.back();
+    scope.in_return = true;
+    VisitReturnBody(ret.body_);
+    scope.in_return = false;
+    return false;  // We handled the traversal ourselves.
+  }
+
+  bool PostVisit(Return & /*unused*/) override {
+    for (const auto &name_symbol : scopes_.back().symbols) curr_return_names_.insert(name_symbol.first);
+    return true;
+  }
+
+  bool PreVisit(With &with) override {
+    auto &scope = scopes_.back();
+    scope.in_with = true;
+    VisitReturnBody(with.body_, with.where_);
+    scope.in_with = false;
+    return false;  // We handled the traversal ourselves.
+  }
+
+  bool PreVisit(Where & /*unused*/) override {
+    scopes_.back().in_where = true;
+    return true;
+  }
+
+  bool PostVisit(Where & /*unused*/) override {
+    scopes_.back().in_where = false;
+    return true;
+  }
+
+  bool PreVisit(Merge & /*unused*/) override {
+    scopes_.back().in_merge = true;
+    return true;
+  }
+
+  bool PostVisit(Merge & /*unused*/) override {
+    scopes_.back().in_merge = false;
+    return true;
+  }
+
+  bool PostVisit(Unwind &unwind) override {
+    const auto &name = unwind.named_expression_->name_;
+    if (HasSymbolLocalScope(name)) {
+      throw RedeclareVariableError(name);
+    }
+    unwind.named_expression_->MapTo(CreateSymbol(name, true));
+    return true;
+  }
+
+  bool PreVisit(Match & /*unused*/) override {
+    scopes_.back().in_match = true;
+    return true;
+  }
+
+  bool PostVisit(Match & /*unused*/) override {
+    auto &scope = scopes_.back();
+    scope.in_match = false;
+    // Check variables in property maps after visiting Match, so that they can
+    // reference symbols out of bind order.
+    for (auto &ident : scope.identifiers_in_match) {
+      if (!HasSymbolLocalScope(ident->name_) && !ConsumePredefinedIdentifier(ident->name_))
+        throw UnboundVariableError(ident->name_);
+      ident->MapTo(scope.symbols[ident->name_]);
+    }
+    scope.identifiers_in_match.clear();
+    return true;
+  }
+
+  bool PreVisit(Foreach &for_each) override {
+    const auto &name = for_each.named_expression_->name_;
+    scopes_.emplace_back(Scope());
+    scopes_.back().in_foreach = true;
+    for_each.named_expression_->MapTo(
+        CreateSymbol(name, true, Symbol::Type::ANY, for_each.named_expression_->token_position_));
+    return true;
+  }
+
+  bool PostVisit(Foreach & /*unused*/) override {
+    scopes_.pop_back();
+    return true;
+  }
+
+  // Expressions
+  ReturnType Visit(Identifier &ident) override {
+    auto &scope = scopes_.back();
+    if (scope.in_skip || scope.in_limit) {
+      throw SemanticException("Variables are not allowed in {}.", scope.in_skip ? "SKIP" : "LIMIT");
+    }
+    Symbol symbol;
+    if (scope.in_pattern && !(scope.in_node_atom || scope.visiting_edge)) {
+      // If we are in the pattern, and outside of a node or an edge, the
+      // identifier is the pattern name.
+      symbol = GetOrCreateSymbolLocalScope(ident.name_, ident.user_declared_, Symbol::Type::PATH);
+    } else if (scope.in_pattern && scope.in_pattern_atom_identifier) {
+      //  Patterns used to create nodes and edges cannot redeclare already
+      //  established bindings. Declaration only happens in single node
+      //  patterns and in edge patterns. OpenCypher example,
+      //  `MATCH (n) CREATE (n)` should throw an error that `n` is already
+      //  declared. While `MATCH (n) CREATE (n) -[:R]-> (n)` is allowed,
+      //  since `n` now references the bound node instead of declaring it.
+      if ((scope.in_create_node || scope.in_create_edge) && HasSymbolLocalScope(ident.name_)) {
+        throw RedeclareVariableError(ident.name_);
+      }
+      auto type = Symbol::Type::VERTEX;
+      if (scope.visiting_edge) {
+        // Edge referencing is not allowed (like in Neo4j):
+        // `MATCH (n) - [r] -> (n) - [r] -> (n) RETURN r` is not allowed.
+        if (HasSymbolLocalScope(ident.name_)) {
+          throw RedeclareVariableError(ident.name_);
+        }
+        type = scope.visiting_edge->IsVariable() ? Symbol::Type::EDGE_LIST : Symbol::Type::EDGE;
+      }
+      symbol = GetOrCreateSymbolLocalScope(ident.name_, ident.user_declared_, type);
+    } else if (scope.in_pattern && !scope.in_pattern_atom_identifier && scope.in_match) {
+      if (scope.in_edge_range && scope.visiting_edge->identifier_->name_ == ident.name_) {
+        // Prevent variable path bounds to reference the identifier which is bound
+        // by the variable path itself.
+        throw UnboundVariableError(ident.name_);
+      }
+      // Variables in property maps or bounds of variable length path during MATCH
+      // can reference symbols bound later in the same MATCH. We collect them
+      // here, so that they can be checked after visiting Match.
+      scope.identifiers_in_match.emplace_back(&ident);
+    } else {
+      // Everything else references a bound symbol.
+      if (!HasSymbol(ident.name_) && !ConsumePredefinedIdentifier(ident.name_)) throw UnboundVariableError(ident.name_);
+      symbol = GetOrCreateSymbol(ident.name_, ident.user_declared_, Symbol::Type::ANY);
+    }
+    ident.MapTo(symbol);
+    return true;
+  }
+
+  ReturnType Visit(PrimitiveLiteral & /*unused*/) override { return true; }
+
+  ReturnType Visit(ParameterLookup & /*unused*/) override { return true; }
+
+  bool PreVisit(Aggregation &aggr) override {
+    auto &scope = scopes_.back();
+    // Check if the aggregation can be used in this context. This check should
+    // probably move to a separate phase, which checks if the query is well
+    // formed.
+    if ((!scope.in_return && !scope.in_with) || scope.in_order_by || scope.in_skip || scope.in_limit ||
+        scope.in_where) {
+      throw SemanticException("Aggregation functions are only allowed in WITH and RETURN.");
+    }
+    if (scope.in_aggregation) {
+      throw SemanticException(
+          "Using aggregation functions inside aggregation functions is not "
+          "allowed.");
+    }
+    if (scope.num_if_operators) {
+      // Neo allows aggregations here and produces very interesting behaviors.
+      // To simplify implementation at this moment we decided to completely
+      // disallow aggregations inside of the CASE.
+      // However, in some cases aggregation makes perfect sense, for example:
+      //    CASE count(n) WHEN 10 THEN "YES" ELSE "NO" END.
+      // TODO: Rethink of allowing aggregations in some parts of the CASE
+      // construct.
+      throw SemanticException("Using aggregation functions inside of CASE is not allowed.");
+    }
+    // Create a virtual symbol for aggregation result.
+    // Currently, we only have aggregation operators which return numbers.
+    auto aggr_name = Aggregation::OpToString(aggr.op_) + std::to_string(aggr.symbol_pos_);
+    aggr.MapTo(CreateSymbol(aggr_name, false, Symbol::Type::NUMBER));
+    scope.in_aggregation = true;
+    scope.has_aggregation = true;
+    return true;
+  }
+
+  bool PostVisit(Aggregation & /*unused*/) override {
+    scopes_.back().in_aggregation = false;
+    return true;
+  }
+
+  bool PreVisit(IfOperator & /*unused*/) override {
+    ++scopes_.back().num_if_operators;
+    return true;
+  }
+
+  bool PostVisit(IfOperator & /*unused*/) override {
+    --scopes_.back().num_if_operators;
+    return true;
+  }
+
+  bool PreVisit(All &all) override {
+    all.list_expression_->Accept(*this);
+    VisitWithIdentifiers(all.where_->expression_, {all.identifier_});
+    return false;
+  }
+
+  bool PreVisit(Single &single) override {
+    single.list_expression_->Accept(*this);
+    VisitWithIdentifiers(single.where_->expression_, {single.identifier_});
+    return false;
+  }
+
+  bool PreVisit(Any &any) override {
+    any.list_expression_->Accept(*this);
+    VisitWithIdentifiers(any.where_->expression_, {any.identifier_});
+    return false;
+  }
+
+  bool PreVisit(None &none) override {
+    none.list_expression_->Accept(*this);
+    VisitWithIdentifiers(none.where_->expression_, {none.identifier_});
+    return false;
+  }
+
+  bool PreVisit(Reduce &reduce) override {
+    reduce.initializer_->Accept(*this);
+    reduce.list_->Accept(*this);
+    VisitWithIdentifiers(reduce.expression_, {reduce.accumulator_, reduce.identifier_});
+    return false;
+  }
+
+  bool PreVisit(Extract &extract) override {
+    extract.list_->Accept(*this);
+    VisitWithIdentifiers(extract.expression_, {extract.identifier_});
+    return false;
+  }
+
+  // Pattern and its subparts.
+  bool PreVisit(Pattern &pattern) override {
+    auto &scope = scopes_.back();
+    scope.in_pattern = true;
+    if ((scope.in_create || scope.in_merge) && pattern.atoms_.size() == 1U) {
+      MG_ASSERT(utils::IsSubtype(*pattern.atoms_[0], NodeAtom::kType), "Expected a single NodeAtom in Pattern");
+      scope.in_create_node = true;
+    }
+    return true;
+  }
+
+  bool PostVisit(Pattern & /*unused*/) override {
+    auto &scope = scopes_.back();
+    scope.in_pattern = false;
+    scope.in_create_node = false;
+    return true;
+  }
+
+  bool PreVisit(NodeAtom &node_atom) override {
+    auto &scope = scopes_.back();
+    auto check_node_semantic = [&node_atom, &scope, this](const bool props_or_labels) {
+      const auto &node_name = node_atom.identifier_->name_;
+      if ((scope.in_create || scope.in_merge) && props_or_labels && HasSymbolLocalScope(node_name)) {
+        throw SemanticException("Cannot create node '" + node_name +
+                                "' with labels or properties, because it is already declared.");
+      }
+      scope.in_pattern_atom_identifier = true;
+      node_atom.identifier_->Accept(*this);
+      scope.in_pattern_atom_identifier = false;
+    };
+
+    scope.in_node_atom = true;
+    if (auto *properties = std::get_if<std::unordered_map<PropertyIx, Expression *>>(&node_atom.properties_)) {
+      bool props_or_labels = !properties->empty() || !node_atom.labels_.empty();
+
+      check_node_semantic(props_or_labels);
+      for (auto kv : *properties) {
+        kv.second->Accept(*this);
+      }
+
+      return false;
+    }
+    auto &properties_parameter = std::get<ParameterLookup *>(node_atom.properties_);
+    bool props_or_labels = !properties_parameter || !node_atom.labels_.empty();
+
+    check_node_semantic(props_or_labels);
+    properties_parameter->Accept(*this);
+    return false;
+  }
+
+  bool PostVisit(NodeAtom & /*unused*/) override {
+    scopes_.back().in_node_atom = false;
+    return true;
+  }
+
+  bool PreVisit(EdgeAtom &edge_atom) override {
+    auto &scope = scopes_.back();
+    scope.visiting_edge = &edge_atom;
+    if (scope.in_create || scope.in_merge) {
+      scope.in_create_edge = true;
+      if (edge_atom.edge_types_.size() != 1U) {
+        throw SemanticException(
+            "A single relationship type must be specified "
+            "when creating an edge.");
+      }
+      if (scope.in_create &&  // Merge allows bidirectionality
+          edge_atom.direction_ == EdgeAtom::Direction::BOTH) {
+        throw SemanticException(
+            "Bidirectional relationship are not supported "
+            "when creating an edge");
+      }
+      if (edge_atom.IsVariable()) {
+        throw SemanticException(
+            "Variable length relationships are not supported when creating an "
+            "edge.");
+      }
+    }
+    if (auto *properties = std::get_if<std::unordered_map<PropertyIx, Expression *>>(&edge_atom.properties_)) {
+      for (auto kv : *properties) {
+        kv.second->Accept(*this);
+      }
+    } else {
+      std::get<ParameterLookup *>(edge_atom.properties_)->Accept(*this);
+    }
+    if (edge_atom.IsVariable()) {
+      scope.in_edge_range = true;
+      if (edge_atom.lower_bound_) {
+        edge_atom.lower_bound_->Accept(*this);
+      }
+      if (edge_atom.upper_bound_) {
+        edge_atom.upper_bound_->Accept(*this);
+      }
+      scope.in_edge_range = false;
+      scope.in_pattern = false;
+      if (edge_atom.filter_lambda_.expression) {
+        VisitWithIdentifiers(edge_atom.filter_lambda_.expression,
+                             {edge_atom.filter_lambda_.inner_edge, edge_atom.filter_lambda_.inner_node});
+      } else {
+        // Create inner symbols, but don't bind them in scope, since they are to
+        // be used in the missing filter expression.
+        auto *inner_edge = edge_atom.filter_lambda_.inner_edge;
+        inner_edge->MapTo(
+            symbol_table_->CreateSymbol(inner_edge->name_, inner_edge->user_declared_, Symbol::Type::EDGE));
+        auto *inner_node = edge_atom.filter_lambda_.inner_node;
+        inner_node->MapTo(
+            symbol_table_->CreateSymbol(inner_node->name_, inner_node->user_declared_, Symbol::Type::VERTEX));
+      }
+      if (edge_atom.weight_lambda_.expression) {
+        VisitWithIdentifiers(edge_atom.weight_lambda_.expression,
+                             {edge_atom.weight_lambda_.inner_edge, edge_atom.weight_lambda_.inner_node});
+      }
+      scope.in_pattern = true;
+    }
+    scope.in_pattern_atom_identifier = true;
+    edge_atom.identifier_->Accept(*this);
+    scope.in_pattern_atom_identifier = false;
+    if (edge_atom.total_weight_) {
+      if (HasSymbolLocalScope(edge_atom.total_weight_->name_)) {
+        throw RedeclareVariableError(edge_atom.total_weight_->name_);
+      }
+      edge_atom.total_weight_->MapTo(GetOrCreateSymbolLocalScope(
+          edge_atom.total_weight_->name_, edge_atom.total_weight_->user_declared_, Symbol::Type::NUMBER));
+    }
+    return false;
+  }
+
+  bool PostVisit(EdgeAtom & /*unused*/) override {
+    auto &scope = scopes_.back();
+    scope.visiting_edge = nullptr;
+    scope.in_create_edge = false;
+    return true;
+  }
+
+ private:
+  // Scope stores the state of where we are when visiting the AST and a map of
+  // names to symbols.
+  struct Scope {
+    bool in_pattern{false};
+    bool in_merge{false};
+    bool in_create{false};
+    // in_create_node is true if we are creating or merging *only* a node.
+    // Therefore, it is *not* equivalent to (in_create || in_merge) &&
+    // in_node_atom.
+    bool in_create_node{false};
+    // True if creating an edge;
+    // shortcut for (in_create || in_merge) && visiting_edge.
+    bool in_create_edge{false};
+    bool in_node_atom{false};
+    EdgeAtom *visiting_edge{nullptr};
+    bool in_aggregation{false};
+    bool in_return{false};
+    bool in_with{false};
+    bool in_skip{false};
+    bool in_limit{false};
+    bool in_order_by{false};
+    bool in_where{false};
+    bool in_match{false};
+    bool in_foreach{false};
+    // True when visiting a pattern atom (node or edge) identifier, which can be
+    // reused or created in the pattern itself.
+    bool in_pattern_atom_identifier{false};
+    // True when visiting range bounds of a variable path.
+    bool in_edge_range{false};
+    // True if the return/with contains an aggregation in any named expression.
+    bool has_aggregation{false};
+    // Map from variable names to symbols.
+    std::map<std::string, Symbol> symbols;
+    // Identifiers found in property maps of patterns or as variable length path
+    // bounds in a single Match clause. They need to be checked after visiting
+    // Match. Identifiers created by naming vertices, edges and paths are *not*
+    // stored in here.
+    std::vector<Identifier *> identifiers_in_match;
+    // Number of nested IfOperators.
+    int num_if_operators{0};
+  };
+
+  inline static std::optional<Symbol> FindSymbolInScope(const std::string &name, const Scope &scope,
+                                                        Symbol::Type type) {
+    if (auto it = scope.symbols.find(name); it != scope.symbols.end()) {
+      const auto &symbol = it->second;
+      // Unless we have `ANY` type, check that types match.
+      if (type != Symbol::Type::ANY && symbol.type() != Symbol::Type::ANY && type != symbol.type()) {
+        throw TypeMismatchError(name, Symbol::TypeToString(symbol.type()), Symbol::TypeToString(type));
+      }
+      return symbol;
+    }
+    return std::nullopt;
+  }
+
+  bool HasSymbol(const std::string &name) const {
+    return std::ranges::any_of(scopes_, [&name](const auto &scope) { return scope.symbols.contains(name); });
+  }
+
+  bool HasSymbolLocalScope(const std::string &name) const { return scopes_.back().symbols.contains(name); }
+
+  // @return true if it added a predefined identifier with that name
+  bool ConsumePredefinedIdentifier(const std::string &name) {
+    auto it = predefined_identifiers_.find(name);
+
+    if (it == predefined_identifiers_.end()) {
+      return false;
+    }
+
+    // we can only use the predefined identifier in a single scope so we remove it after creating
+    // a symbol for it
+    auto &identifier = it->second;
+    MG_ASSERT(!identifier->user_declared_, "Predefined symbols cannot be user declared!");
+    identifier->MapTo(CreateSymbol(identifier->name_, identifier->user_declared_));
+    predefined_identifiers_.erase(it);
+    return true;
+  }
+
+  // Returns a freshly generated symbol. Previous mapping of the same name to a
+  // different symbol is replaced with the new one.
+  Symbol CreateSymbol(const std::string &name, bool user_declared, Symbol::Type type = Symbol::Type::ANY,
+                      int token_position = -1) {
+    auto symbol = symbol_table_->CreateSymbol(name, user_declared, type, token_position);
+    scopes_.back().symbols[name] = symbol;
+    return symbol;
+  }
+
+  Symbol GetOrCreateSymbol(const std::string &name, bool user_declared, Symbol::Type type = Symbol::Type::ANY) {
+    // NOLINTNEXTLINE
+    for (auto scope = scopes_.rbegin(); scope != scopes_.rend(); ++scope) {
+      if (auto maybe_symbol = FindSymbolInScope(name, *scope, type); maybe_symbol) {
+        return *maybe_symbol;
+      }
+    }
+    return CreateSymbol(name, user_declared, type);
+  }
+
+  // Returns the symbol by name. If the mapping already exists, checks if the
+  // types match. Otherwise, returns a new symbol.
+  Symbol GetOrCreateSymbolLocalScope(const std::string &name, bool user_declared,
+                                     Symbol::Type type = Symbol::Type::ANY) {
+    auto &scope = scopes_.back();
+    if (auto maybe_symbol = FindSymbolInScope(name, scope, type); maybe_symbol) {
+      return *maybe_symbol;
+    }
+    return CreateSymbol(name, user_declared, type);
+  }
+
+  void VisitReturnBody(ReturnBody &body, Where *where = nullptr) {
+    auto &scope = scopes_.back();
+    for (auto &expr : body.named_expressions) {
+      expr->Accept(*this);
+    }
+    std::vector<Symbol> user_symbols;
+    if (body.all_identifiers) {
+      // Carry over user symbols because '*' appeared.
+      for (const auto &sym_pair : scope.symbols) {
+        if (!sym_pair.second.user_declared()) {
+          continue;
+        }
+        user_symbols.emplace_back(sym_pair.second);
+      }
+      if (user_symbols.empty()) {
+        throw SemanticException("There are no variables in scope to use for '*'.");
+      }
+    }
+    // WITH/RETURN clause removes declarations of all the previous variables and
+    // declares only those established through named expressions. New declarations
+    // must not be visible inside named expressions themselves.
+    bool removed_old_names = false;
+    if ((!where && body.order_by.empty()) || scope.has_aggregation) {
+      // WHERE and ORDER BY need to see both the old and new symbols, unless we
+      // have an aggregation. Therefore, we can clear the symbols immediately if
+      // there is neither ORDER BY nor WHERE, or we have an aggregation.
+      scope.symbols.clear();
+      removed_old_names = true;
+    }
+    // Create symbols for named expressions.
+    std::unordered_set<std::string> new_names;
+    for (const auto &user_sym : user_symbols) {
+      new_names.insert(user_sym.name());
+      scope.symbols[user_sym.name()] = user_sym;
+    }
+    for (auto &named_expr : body.named_expressions) {
+      const auto &name = named_expr->name_;
+      if (!new_names.insert(name).second) {
+        throw SemanticException("Multiple results with the same name '{}' are not allowed.", name);
+      }
+      // An improvement would be to infer the type of the expression, so that the
+      // new symbol would have a more specific type.
+      named_expr->MapTo(CreateSymbol(name, true, Symbol::Type::ANY, named_expr->token_position_));
+    }
+    scope.in_order_by = true;
+    for (const auto &order_pair : body.order_by) {
+      order_pair.expression->Accept(*this);
+    }
+    scope.in_order_by = false;
+    if (body.skip) {
+      scope.in_skip = true;
+      body.skip->Accept(*this);
+      scope.in_skip = false;
+    }
+    if (body.limit) {
+      scope.in_limit = true;
+      body.limit->Accept(*this);
+      scope.in_limit = false;
+    }
+    if (where) where->Accept(*this);
+    if (!removed_old_names) {
+      // We have an ORDER BY or WHERE, but no aggregation, which means we didn't
+      // clear the old symbols, so do it now. We cannot just call clear, because
+      // we've added new symbols.
+      for (auto sym_it = scope.symbols.begin(); sym_it != scope.symbols.end();) {
+        if (new_names.find(sym_it->first) == new_names.end()) {
+          sym_it = scope.symbols.erase(sym_it);
+        } else {
+          sym_it++;
+        }
+      }
+    }
+    scopes_.back().has_aggregation = false;
+  }
+
+  void VisitWithIdentifiers(Expression *expr, const std::vector<Identifier *> &identifiers) {
+    auto &scope = scopes_.back();
+    std::vector<std::pair<std::optional<Symbol>, Identifier *>> prev_symbols;
+    // Collect previous symbols if they exist.
+    for (const auto &identifier : identifiers) {
+      std::optional<Symbol> prev_symbol;
+      auto prev_symbol_it = scope.symbols.find(identifier->name_);
+      if (prev_symbol_it != scope.symbols.end()) {
+        prev_symbol = prev_symbol_it->second;
+      }
+      identifier->MapTo(CreateSymbol(identifier->name_, identifier->user_declared_));
+      prev_symbols.emplace_back(prev_symbol, identifier);
+    }
+    // Visit the expression with the new symbols bound.
+    expr->Accept(*this);
+    // Restore back to previous symbols.
+    for (const auto &prev : prev_symbols) {
+      const auto &prev_symbol = prev.first;
+      const auto &identifier = prev.second;
+      if (prev_symbol) {
+        scope.symbols[identifier->name_] = *prev_symbol;
+      } else {
+        scope.symbols.erase(identifier->name_);
+      }
+    }
+  }
+
+  SymbolTable *symbol_table_;
+
+  // Identifiers which are injected from outside the query. Each identifier
+  // is mapped by its name.
+  std::unordered_map<std::string, Identifier *> predefined_identifiers_;
+  std::vector<Scope> scopes_;
+  std::unordered_set<std::string> prev_return_names_;
+  std::unordered_set<std::string> curr_return_names_;
+};
+
+inline SymbolTable MakeSymbolTable(CypherQuery *query, const std::vector<Identifier *> &predefined_identifiers = {}) {
+  SymbolTable symbol_table;
+  SymbolGenerator symbol_generator(&symbol_table, predefined_identifiers);
+  query->single_query_->Accept(symbol_generator);
+  for (auto *cypher_union : query->cypher_unions_) {
+    cypher_union->Accept(symbol_generator);
+  }
+  return symbol_table;
+}
+
+}  // namespace memgraph::expr

src/expr/semantic/symbol_table.hpp

@@ -14,11 +14,11 @@
 #include <map>
 #include <string>
 
-#include "query/v2/frontend/ast/ast.hpp"
-#include "query/v2/frontend/semantic/symbol.hpp"
+#include "expr/ast.hpp"
+#include "expr/semantic/symbol.hpp"
 #include "utils/logging.hpp"
 
-namespace memgraph::query::v2 {
+namespace memgraph::expr {
 
 class SymbolTable final {
  public:
@@ -61,4 +61,4 @@ class SymbolTable final {
   std::map<int32_t, Symbol> table_;
 };
 
-}  // namespace memgraph::query::v2
+}  // namespace memgraph::expr

src/glue/auth.cpp

@@ -57,8 +57,6 @@ auth::Permission PrivilegeToPermission(query::AuthQuery::Privilege privilege) {
       return auth::Permission::MODULE_WRITE;
     case query::AuthQuery::Privilege::WEBSOCKET:
       return auth::Permission::WEBSOCKET;
-    case query::AuthQuery::Privilege::SCHEMA:
-      return auth::Permission::SCHEMA;
   }
 }
 }  // namespace memgraph::glue

src/glue/v2/auth.cpp

@@ -0,0 +1,64 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "glue/v2/auth.hpp"
+
+namespace memgraph::glue::v2 {
+
+auth::Permission PrivilegeToPermission(query::v2::AuthQuery::Privilege privilege) {
+  switch (privilege) {
+    case query::v2::AuthQuery::Privilege::MATCH:
+      return auth::Permission::MATCH;
+    case query::v2::AuthQuery::Privilege::CREATE:
+      return auth::Permission::CREATE;
+    case query::v2::AuthQuery::Privilege::MERGE:
+      return auth::Permission::MERGE;
+    case query::v2::AuthQuery::Privilege::DELETE:
+      return auth::Permission::DELETE;
+    case query::v2::AuthQuery::Privilege::SET:
+      return auth::Permission::SET;
+    case query::v2::AuthQuery::Privilege::REMOVE:
+      return auth::Permission::REMOVE;
+    case query::v2::AuthQuery::Privilege::INDEX:
+      return auth::Permission::INDEX;
+    case query::v2::AuthQuery::Privilege::STATS:
+      return auth::Permission::STATS;
+    case query::v2::AuthQuery::Privilege::CONSTRAINT:
+      return auth::Permission::CONSTRAINT;
+    case query::v2::AuthQuery::Privilege::DUMP:
+      return auth::Permission::DUMP;
+    case query::v2::AuthQuery::Privilege::REPLICATION:
+      return auth::Permission::REPLICATION;
+    case query::v2::AuthQuery::Privilege::DURABILITY:
+      return auth::Permission::DURABILITY;
+    case query::v2::AuthQuery::Privilege::READ_FILE:
+      return auth::Permission::READ_FILE;
+    case query::v2::AuthQuery::Privilege::FREE_MEMORY:
+      return auth::Permission::FREE_MEMORY;
+    case query::v2::AuthQuery::Privilege::TRIGGER:
+      return auth::Permission::TRIGGER;
+    case query::v2::AuthQuery::Privilege::CONFIG:
+      return auth::Permission::CONFIG;
+    case query::v2::AuthQuery::Privilege::AUTH:
+      return auth::Permission::AUTH;
+    case query::v2::AuthQuery::Privilege::STREAM:
+      return auth::Permission::STREAM;
+    case query::v2::AuthQuery::Privilege::MODULE_READ:
+      return auth::Permission::MODULE_READ;
+    case query::v2::AuthQuery::Privilege::MODULE_WRITE:
+      return auth::Permission::MODULE_WRITE;
+    case query::v2::AuthQuery::Privilege::WEBSOCKET:
+      return auth::Permission::WEBSOCKET;
+    case query::v2::AuthQuery::Privilege::SCHEMA:
+      return auth::Permission::SCHEMA;
+  }
+}
+}  // namespace memgraph::glue::v2

src/glue/v2/auth.hpp

@@ -0,0 +1,23 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "auth/models.hpp"
+#include "query/v2/frontend/ast/ast.hpp"
+
+namespace memgraph::glue::v2 {
+
+/**
+ * This function converts query::AuthQuery::Privilege to its corresponding
+ * auth::Permission.
+ */
+auth::Permission PrivilegeToPermission(query::v2::AuthQuery::Privilege privilege);
+
+}  // namespace memgraph::glue::v2

src/glue/v2/communication.cpp

@@ -0,0 +1,277 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "glue/v2/communication.hpp"
+
+#include <map>
+#include <string>
+#include <vector>
+
+#include "storage/v3/edge_accessor.hpp"
+#include "storage/v3/shard.hpp"
+#include "storage/v3/vertex_accessor.hpp"
+#include "utils/temporal.hpp"
+
+using memgraph::communication::bolt::Value;
+
+namespace memgraph::glue::v2 {
+
+query::v2::TypedValue ToTypedValue(const Value &value) {
+  switch (value.type()) {
+    case Value::Type::Null:
+      return {};
+    case Value::Type::Bool:
+      return query::v2::TypedValue(value.ValueBool());
+    case Value::Type::Int:
+      return query::v2::TypedValue(value.ValueInt());
+    case Value::Type::Double:
+      return query::v2::TypedValue(value.ValueDouble());
+    case Value::Type::String:
+      return query::v2::TypedValue(value.ValueString());
+    case Value::Type::List: {
+      std::vector<query::v2::TypedValue> list;
+      list.reserve(value.ValueList().size());
+      for (const auto &v : value.ValueList()) list.push_back(ToTypedValue(v));
+      return query::v2::TypedValue(std::move(list));
+    }
+    case Value::Type::Map: {
+      std::map<std::string, query::v2::TypedValue> map;
+      for (const auto &kv : value.ValueMap()) map.emplace(kv.first, ToTypedValue(kv.second));
+      return query::v2::TypedValue(std::move(map));
+    }
+    case Value::Type::Vertex:
+    case Value::Type::Edge:
+    case Value::Type::UnboundedEdge:
+    case Value::Type::Path:
+      throw communication::bolt::ValueException("Unsupported conversion from Value to TypedValue");
+    case Value::Type::Date:
+      return query::v2::TypedValue(value.ValueDate());
+    case Value::Type::LocalTime:
+      return query::v2::TypedValue(value.ValueLocalTime());
+    case Value::Type::LocalDateTime:
+      return query::v2::TypedValue(value.ValueLocalDateTime());
+    case Value::Type::Duration:
+      return query::v2::TypedValue(value.ValueDuration());
+  }
+}
+
+storage::v3::Result<communication::bolt::Vertex> ToBoltVertex(const query::v2::VertexAccessor &vertex,
+                                                              const storage::v3::Shard &db, storage::v3::View view) {
+  return ToBoltVertex(vertex.impl_, db, view);
+}
+
+storage::v3::Result<communication::bolt::Edge> ToBoltEdge(const query::v2::EdgeAccessor &edge,
+                                                          const storage::v3::Shard &db, storage::v3::View view) {
+  return ToBoltEdge(edge.impl_, db, view);
+}
+
+storage::v3::Result<Value> ToBoltValue(const query::v2::TypedValue &value, const storage::v3::Shard &db,
+                                       storage::v3::View view) {
+  switch (value.type()) {
+    case query::v2::TypedValue::Type::Null:
+      return Value();
+    case query::v2::TypedValue::Type::Bool:
+      return Value(value.ValueBool());
+    case query::v2::TypedValue::Type::Int:
+      return Value(value.ValueInt());
+    case query::v2::TypedValue::Type::Double:
+      return Value(value.ValueDouble());
+    case query::v2::TypedValue::Type::String:
+      return Value(std::string(value.ValueString()));
+    case query::v2::TypedValue::Type::List: {
+      std::vector<Value> values;
+      values.reserve(value.ValueList().size());
+      for (const auto &v : value.ValueList()) {
+        auto maybe_value = ToBoltValue(v, db, view);
+        if (maybe_value.HasError()) return maybe_value.GetError();
+        values.emplace_back(std::move(*maybe_value));
+      }
+      return Value(std::move(values));
+    }
+    case query::v2::TypedValue::Type::Map: {
+      std::map<std::string, Value> map;
+      for (const auto &kv : value.ValueMap()) {
+        auto maybe_value = ToBoltValue(kv.second, db, view);
+        if (maybe_value.HasError()) return maybe_value.GetError();
+        map.emplace(kv.first, std::move(*maybe_value));
+      }
+      return Value(std::move(map));
+    }
+    case query::v2::TypedValue::Type::Vertex: {
+      auto maybe_vertex = ToBoltVertex(value.ValueVertex(), db, view);
+      if (maybe_vertex.HasError()) return maybe_vertex.GetError();
+      return Value(std::move(*maybe_vertex));
+    }
+    case query::v2::TypedValue::Type::Edge: {
+      auto maybe_edge = ToBoltEdge(value.ValueEdge(), db, view);
+      if (maybe_edge.HasError()) return maybe_edge.GetError();
+      return Value(std::move(*maybe_edge));
+    }
+    case query::v2::TypedValue::Type::Path: {
+      auto maybe_path = ToBoltPath(value.ValuePath(), db, view);
+      if (maybe_path.HasError()) return maybe_path.GetError();
+      return Value(std::move(*maybe_path));
+    }
+    case query::v2::TypedValue::Type::Date:
+      return Value(value.ValueDate());
+    case query::v2::TypedValue::Type::LocalTime:
+      return Value(value.ValueLocalTime());
+    case query::v2::TypedValue::Type::LocalDateTime:
+      return Value(value.ValueLocalDateTime());
+    case query::v2::TypedValue::Type::Duration:
+      return Value(value.ValueDuration());
+  }
+}
+
+storage::v3::Result<communication::bolt::Vertex> ToBoltVertex(const storage::v3::VertexAccessor &vertex,
+                                                              const storage::v3::Shard &db, storage::v3::View view) {
+  // TODO(jbajic) Fix bolt communication
+  auto id = communication::bolt::Id::FromUint(0);
+  auto maybe_labels = vertex.Labels(view);
+  if (maybe_labels.HasError()) return maybe_labels.GetError();
+  std::vector<std::string> labels;
+  labels.reserve(maybe_labels->size());
+  for (const auto &label : *maybe_labels) {
+    labels.push_back(db.LabelToName(label));
+  }
+  auto maybe_properties = vertex.Properties(view);
+  if (maybe_properties.HasError()) return maybe_properties.GetError();
+  std::map<std::string, Value> properties;
+  for (const auto &prop : *maybe_properties) {
+    properties[db.PropertyToName(prop.first)] = ToBoltValue(prop.second);
+  }
+  return communication::bolt::Vertex{id, labels, properties};
+}
+
+storage::v3::Result<communication::bolt::Edge> ToBoltEdge(const storage::v3::EdgeAccessor &edge,
+                                                          const storage::v3::Shard &db, storage::v3::View view) {
+  // TODO(jbajic) Fix bolt communication
+  auto id = communication::bolt::Id::FromUint(0);
+  auto from = communication::bolt::Id::FromUint(0);
+  auto to = communication::bolt::Id::FromUint(0);
+  const auto &type = db.EdgeTypeToName(edge.EdgeType());
+  auto maybe_properties = edge.Properties(view);
+  if (maybe_properties.HasError()) return maybe_properties.GetError();
+  std::map<std::string, Value> properties;
+  for (const auto &prop : *maybe_properties) {
+    properties[db.PropertyToName(prop.first)] = ToBoltValue(prop.second);
+  }
+  return communication::bolt::Edge{id, from, to, type, properties};
+}
+
+storage::v3::Result<communication::bolt::Path> ToBoltPath(const query::v2::Path &path, const storage::v3::Shard &db,
+                                                          storage::v3::View view) {
+  std::vector<communication::bolt::Vertex> vertices;
+  vertices.reserve(path.vertices().size());
+  for (const auto &v : path.vertices()) {
+    auto maybe_vertex = ToBoltVertex(v, db, view);
+    if (maybe_vertex.HasError()) return maybe_vertex.GetError();
+    vertices.emplace_back(std::move(*maybe_vertex));
+  }
+  std::vector<communication::bolt::Edge> edges;
+  edges.reserve(path.edges().size());
+  for (const auto &e : path.edges()) {
+    auto maybe_edge = ToBoltEdge(e, db, view);
+    if (maybe_edge.HasError()) return maybe_edge.GetError();
+    edges.emplace_back(std::move(*maybe_edge));
+  }
+  return communication::bolt::Path(vertices, edges);
+}
+
+storage::v3::PropertyValue ToPropertyValue(const Value &value) {
+  switch (value.type()) {
+    case Value::Type::Null:
+      return {};
+    case Value::Type::Bool:
+      return storage::v3::PropertyValue(value.ValueBool());
+    case Value::Type::Int:
+      return storage::v3::PropertyValue(value.ValueInt());
+    case Value::Type::Double:
+      return storage::v3::PropertyValue(value.ValueDouble());
+    case Value::Type::String:
+      return storage::v3::PropertyValue(value.ValueString());
+    case Value::Type::List: {
+      std::vector<storage::v3::PropertyValue> vec;
+      vec.reserve(value.ValueList().size());
+      for (const auto &value : value.ValueList()) vec.emplace_back(ToPropertyValue(value));
+      return storage::v3::PropertyValue(std::move(vec));
+    }
+    case Value::Type::Map: {
+      std::map<std::string, storage::v3::PropertyValue> map;
+      for (const auto &kv : value.ValueMap()) map.emplace(kv.first, ToPropertyValue(kv.second));
+      return storage::v3::PropertyValue(std::move(map));
+    }
+    case Value::Type::Vertex:
+    case Value::Type::Edge:
+    case Value::Type::UnboundedEdge:
+    case Value::Type::Path:
+      throw communication::bolt::ValueException("Unsupported conversion from Value to PropertyValue");
+    case Value::Type::Date:
+      return storage::v3::PropertyValue(
+          storage::v3::TemporalData(storage::v3::TemporalType::Date, value.ValueDate().MicrosecondsSinceEpoch()));
+    case Value::Type::LocalTime:
+      return storage::v3::PropertyValue(storage::v3::TemporalData(storage::v3::TemporalType::LocalTime,
+                                                                  value.ValueLocalTime().MicrosecondsSinceEpoch()));
+    case Value::Type::LocalDateTime:
+      return storage::v3::PropertyValue(storage::v3::TemporalData(storage::v3::TemporalType::LocalDateTime,
+                                                                  value.ValueLocalDateTime().MicrosecondsSinceEpoch()));
+    case Value::Type::Duration:
+      return storage::v3::PropertyValue(
+          storage::v3::TemporalData(storage::v3::TemporalType::Duration, value.ValueDuration().microseconds));
+  }
+}
+
+Value ToBoltValue(const storage::v3::PropertyValue &value) {
+  switch (value.type()) {
+    case storage::v3::PropertyValue::Type::Null:
+      return {};
+    case storage::v3::PropertyValue::Type::Bool:
+      return {value.ValueBool()};
+    case storage::v3::PropertyValue::Type::Int:
+      return {value.ValueInt()};
+      break;
+    case storage::v3::PropertyValue::Type::Double:
+      return {value.ValueDouble()};
+    case storage::v3::PropertyValue::Type::String:
+      return {value.ValueString()};
+    case storage::v3::PropertyValue::Type::List: {
+      const auto &values = value.ValueList();
+      std::vector<Value> vec;
+      vec.reserve(values.size());
+      for (const auto &v : values) {
+        vec.push_back(ToBoltValue(v));
+      }
+      return {std::move(vec)};
+    }
+    case storage::v3::PropertyValue::Type::Map: {
+      const auto &map = value.ValueMap();
+      std::map<std::string, Value> dv_map;
+      for (const auto &kv : map) {
+        dv_map.emplace(kv.first, ToBoltValue(kv.second));
+      }
+      return {std::move(dv_map)};
+    }
+    case storage::v3::PropertyValue::Type::TemporalData:
+      const auto &type = value.ValueTemporalData();
+      switch (type.type) {
+        case storage::v3::TemporalType::Date:
+          return {utils::Date(type.microseconds)};
+        case storage::v3::TemporalType::LocalTime:
+          return {utils::LocalTime(type.microseconds)};
+        case storage::v3::TemporalType::LocalDateTime:
+          return {utils::LocalDateTime(type.microseconds)};
+        case storage::v3::TemporalType::Duration:
+          return {utils::Duration(type.microseconds)};
+      }
+  }
+}
+
+}  // namespace memgraph::glue::v2

src/glue/v2/communication.hpp

@@ -0,0 +1,68 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+/// @file Conversion functions between Value and other memgraph types.
+#pragma once
+
+#include "communication/bolt/v1/value.hpp"
+#include "query/v2/bindings/typed_value.hpp"
+#include "storage/v3/property_value.hpp"
+#include "storage/v3/result.hpp"
+#include "storage/v3/view.hpp"
+
+namespace memgraph::storage::v3 {
+class EdgeAccessor;
+class Storage;
+class VertexAccessor;
+}  // namespace memgraph::storage::v3
+
+namespace memgraph::glue::v2 {
+
+/// @param storage::v3::VertexAccessor for converting to
+///        communication::bolt::Vertex.
+/// @param storage::v3::Shard for getting label and property names.
+/// @param storage::v3::View for deciding which vertex attributes are visible.
+///
+/// @throw std::bad_alloc
+storage::v3::Result<communication::bolt::Vertex> ToBoltVertex(const storage::v3::VertexAccessor &vertex,
+                                                              const storage::v3::Shard &db, storage::v3::View view);
+
+/// @param storage::v3::EdgeAccessor for converting to communication::bolt::Edge.
+/// @param storage::v3::Shard for getting edge type and property names.
+/// @param storage::v3::View for deciding which edge attributes are visible.
+///
+/// @throw std::bad_alloc
+storage::v3::Result<communication::bolt::Edge> ToBoltEdge(const storage::v3::EdgeAccessor &edge,
+                                                          const storage::v3::Shard &db, storage::v3::View view);
+
+/// @param query::v2::Path for converting to communication::bolt::Path.
+/// @param storage::v3::Shard for ToBoltVertex and ToBoltEdge.
+/// @param storage::v3::View for ToBoltVertex and ToBoltEdge.
+///
+/// @throw std::bad_alloc
+storage::v3::Result<communication::bolt::Path> ToBoltPath(const query::v2::Path &path, const storage::v3::Shard &db,
+                                                          storage::v3::View view);
+
+/// @param query::v2::TypedValue for converting to communication::bolt::Value.
+/// @param storage::v3::Shard for ToBoltVertex and ToBoltEdge.
+/// @param storage::v3::View for ToBoltVertex and ToBoltEdge.
+///
+/// @throw std::bad_alloc
+storage::v3::Result<communication::bolt::Value> ToBoltValue(const query::v2::TypedValue &value,
+                                                            const storage::v3::Shard &db, storage::v3::View view);
+
+query::v2::TypedValue ToTypedValue(const communication::bolt::Value &value);
+
+communication::bolt::Value ToBoltValue(const storage::v3::PropertyValue &value);
+
+storage::v3::PropertyValue ToPropertyValue(const communication::bolt::Value &value);
+
+}  // namespace memgraph::glue::v2

src/io/address.hpp

@@ -0,0 +1,77 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <compare>
+
+#include <fmt/format.h>
+#include <boost/asio/ip/tcp.hpp>
+#include <boost/uuid/uuid.hpp>
+#include <boost/uuid/uuid_generators.hpp>
+#include <boost/uuid/uuid_io.hpp>
+
+namespace memgraph::io {
+struct Address {
+  // It's important for all participants to have a
+  // unique identifier - IP and port alone are not
+  // enough, and may change over the lifecycle of
+  // the nodes. Particularly storage nodes may change
+  // their IP addresses over time, and the system
+  // should gracefully update its information
+  // about them.
+  boost::uuids::uuid unique_id;
+  boost::asio::ip::address last_known_ip;
+  uint16_t last_known_port;
+
+  static Address TestAddress(uint16_t port) {
+    return Address{
+        .unique_id = boost::uuids::uuid{boost::uuids::random_generator()()},
+        .last_known_port = port,
+    };
+  }
+
+  static Address UniqueLocalAddress() {
+    return Address{
+        .unique_id = boost::uuids::uuid{boost::uuids::random_generator()()},
+    };
+  }
+
+  /// Returns a new ID with the same IP and port but a unique UUID.
+  Address ForkUniqueAddress() {
+    return Address{
+        .unique_id = boost::uuids::uuid{boost::uuids::random_generator()()},
+        .last_known_ip = last_known_ip,
+        .last_known_port = last_known_port,
+    };
+  }
+
+  friend bool operator==(const Address &lhs, const Address &rhs) = default;
+
+  /// unique_id is most dominant for ordering, then last_known_ip, then last_known_port
+  friend bool operator<(const Address &lhs, const Address &rhs) {
+    if (lhs.unique_id != rhs.unique_id) {
+      return lhs.unique_id < rhs.unique_id;
+    }
+
+    if (lhs.last_known_ip != rhs.last_known_ip) {
+      return lhs.last_known_ip < rhs.last_known_ip;
+    }
+
+    return lhs.last_known_port < rhs.last_known_port;
+  }
+
+  std::string ToString() const {
+    return fmt::format("Address {{ unique_id: {}, last_known_ip: {}, last_known_port: {} }}",
+                       boost::uuids::to_string(unique_id), last_known_ip.to_string(), last_known_port);
+  }
+};
+};  // namespace memgraph::io

src/io/errors.hpp

@@ -0,0 +1,26 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+namespace memgraph::io {
+// Signifies that a retriable operation was unable to
+// complete after a configured number of retries.
+struct RetriesExhausted {};
+
+// Signifies that a request was unable to receive a response
+// within some configured timeout duration. It is important
+// to remember that in distributed systems, a timeout does
+// not signify that a request was not received or processed.
+// It may be the case that the request was fully processed
+// but that the response was not received.
+struct TimedOut {};
+};  // namespace memgraph::io

src/io/future.hpp

@@ -0,0 +1,256 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <condition_variable>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <thread>
+#include <utility>
+
+#include "io/errors.hpp"
+#include "utils/logging.hpp"
+
+namespace memgraph::io {
+
+// Shared is in an anonymous namespace, and the only way to
+// construct a Promise or Future is to pass a Shared in. This
+// ensures that Promises and Futures can only be constructed
+// in this translation unit.
+namespace details {
+template <typename T>
+class Shared {
+  mutable std::condition_variable cv_;
+  mutable std::mutex mu_;
+  std::optional<T> item_;
+  bool consumed_ = false;
+  bool waiting_ = false;
+  std::function<bool()> simulator_notifier_ = nullptr;
+
+ public:
+  explicit Shared(std::function<bool()> simulator_notifier) : simulator_notifier_(simulator_notifier) {}
+  Shared() = default;
+  Shared(Shared &&) = delete;
+  Shared &operator=(Shared &&) = delete;
+  Shared(const Shared &) = delete;
+  Shared &operator=(const Shared &) = delete;
+  ~Shared() = default;
+
+  /// Takes the item out of our optional item_ and returns it.
+  T Take() {
+    MG_ASSERT(item_, "Take called without item_ being present");
+    MG_ASSERT(!consumed_, "Take called on already-consumed Future");
+
+    T ret = std::move(item_).value();
+    item_.reset();
+
+    consumed_ = true;
+
+    return ret;
+  }
+
+  T Wait() {
+    std::unique_lock<std::mutex> lock(mu_);
+    waiting_ = true;
+
+    while (!item_) {
+      bool simulator_progressed = false;
+      if (simulator_notifier_) [[unlikely]] {
+        // We can't hold our own lock while notifying
+        // the simulator because notifying the simulator
+        // involves acquiring the simulator's mutex
+        // to guarantee that our notification linearizes
+        // with the simulator's condition variable.
+        // However, the simulator may acquire our
+        // mutex to check if we are being awaited,
+        // while determining system quiescence,
+        // so we have to get out of its way to avoid
+        // a cyclical deadlock.
+        lock.unlock();
+        simulator_progressed = std::invoke(simulator_notifier_);
+        lock.lock();
+        if (item_) {
+          // item may have been filled while we
+          // had dropped our mutex while notifying
+          // the simulator of our waiting_ status.
+          break;
+        }
+      }
+      if (!simulator_progressed) [[likely]] {
+        cv_.wait(lock);
+      }
+      MG_ASSERT(!consumed_, "Future consumed twice!");
+    }
+
+    waiting_ = false;
+
+    return Take();
+  }
+
+  bool IsReady() const {
+    std::unique_lock<std::mutex> lock(mu_);
+    return item_.has_value();
+  }
+
+  std::optional<T> TryGet() {
+    std::unique_lock<std::mutex> lock(mu_);
+
+    if (item_) {
+      return Take();
+    }
+
+    return std::nullopt;
+  }
+
+  void Fill(T item) {
+    {
+      std::unique_lock<std::mutex> lock(mu_);
+
+      MG_ASSERT(!consumed_, "Promise filled after it was already consumed!");
+      MG_ASSERT(!item_, "Promise filled twice!");
+
+      item_ = item;
+    }  // lock released before condition variable notification
+
+    cv_.notify_all();
+  }
+
+  bool IsAwaited() const {
+    std::unique_lock<std::mutex> lock(mu_);
+    return waiting_;
+  }
+};
+}  // namespace details
+
+template <typename T>
+class Future {
+  bool consumed_or_moved_ = false;
+  std::shared_ptr<details::Shared<T>> shared_;
+
+ public:
+  explicit Future(std::shared_ptr<details::Shared<T>> shared) : shared_(shared) {}
+
+  Future() = delete;
+  Future(Future &&old) noexcept {
+    MG_ASSERT(!old.consumed_or_moved_, "Future moved from after already being moved from or consumed.");
+    shared_ = std::move(old.shared_);
+    consumed_or_moved_ = old.consumed_or_moved_;
+    old.consumed_or_moved_ = true;
+  }
+
+  Future(const Future &) = delete;
+  Future &operator=(const Future &) = delete;
+  ~Future() = default;
+
+  /// Returns true if the Future is ready to
+  /// be consumed using TryGet or Wait (prefer Wait
+  /// if you know it's ready, because it doesn't
+  /// return an optional.
+  bool IsReady() {
+    MG_ASSERT(!consumed_or_moved_, "Called IsReady after Future already consumed!");
+    return shared_->IsReady();
+  }
+
+  /// Non-blocking method that returns the inner
+  /// item if it's already ready, or std::nullopt
+  /// if it is not ready yet.
+  std::optional<T> TryGet() {
+    MG_ASSERT(!consumed_or_moved_, "Called TryGet after Future already consumed!");
+    std::optional<T> ret = shared_->TryGet();
+    if (ret) {
+      consumed_or_moved_ = true;
+    }
+    return ret;
+  }
+
+  /// Block on the corresponding promise to be filled,
+  /// returning the inner item when ready.
+  T Wait() && {
+    MG_ASSERT(!consumed_or_moved_, "Future should only be consumed with Wait once!");
+    T ret = shared_->Wait();
+    consumed_or_moved_ = true;
+    return ret;
+  }
+
+  /// Marks this Future as canceled.
+  void Cancel() {
+    MG_ASSERT(!consumed_or_moved_, "Future::Cancel called on a future that was already moved or consumed!");
+    consumed_or_moved_ = true;
+  }
+};
+
+template <typename T>
+class Promise {
+  std::shared_ptr<details::Shared<T>> shared_;
+  bool filled_or_moved_ = false;
+
+ public:
+  explicit Promise(std::shared_ptr<details::Shared<T>> shared) : shared_(shared) {}
+
+  Promise() = delete;
+  Promise(Promise &&old) noexcept {
+    MG_ASSERT(!old.filled_or_moved_, "Promise moved from after already being moved from or filled.");
+    shared_ = std::move(old.shared_);
+    old.filled_or_moved_ = true;
+  }
+
+  Promise &operator=(Promise &&old) noexcept {
+    MG_ASSERT(!old.filled_or_moved_, "Promise moved from after already being moved from or filled.");
+    shared_ = std::move(old.shared_);
+    old.filled_or_moved_ = true;
+  }
+  Promise(const Promise &) = delete;
+  Promise &operator=(const Promise &) = delete;
+
+  ~Promise() { MG_ASSERT(filled_or_moved_, "Promise destroyed before its associated Future was filled!"); }
+
+  // Fill the expected item into the Future.
+  void Fill(T item) {
+    MG_ASSERT(!filled_or_moved_, "Promise::Fill called on a promise that is already filled or moved!");
+    shared_->Fill(item);
+    filled_or_moved_ = true;
+  }
+
+  bool IsAwaited() { return shared_->IsAwaited(); }
+
+  /// Moves this Promise into a unique_ptr.
+  std::unique_ptr<Promise<T>> ToUnique() && {
+    std::unique_ptr<Promise<T>> up = std::make_unique<Promise<T>>(std::move(shared_));
+
+    filled_or_moved_ = true;
+
+    return up;
+  }
+};
+
+template <typename T>
+std::pair<Future<T>, Promise<T>> FuturePromisePair() {
+  std::shared_ptr<details::Shared<T>> shared = std::make_shared<details::Shared<T>>();
+
+  Future<T> future = Future<T>(shared);
+  Promise<T> promise = Promise<T>(shared);
+
+  return std::make_pair(std::move(future), std::move(promise));
+}
+
+template <typename T>
+std::pair<Future<T>, Promise<T>> FuturePromisePairWithNotifier(std::function<bool()> simulator_notifier) {
+  std::shared_ptr<details::Shared<T>> shared = std::make_shared<details::Shared<T>>(simulator_notifier);
+
+  Future<T> future = Future<T>(shared);
+  Promise<T> promise = Promise<T>(shared);
+
+  return std::make_pair(std::move(future), std::move(promise));
+}
+
+};  // namespace memgraph::io

src/io/local_transport/local_system.hpp

@@ -0,0 +1,35 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <random>
+
+#include "io/address.hpp"
+#include "io/local_transport/local_transport.hpp"
+#include "io/local_transport/local_transport_handle.hpp"
+#include "io/transport.hpp"
+
+namespace memgraph::io::local_transport {
+
+class LocalSystem {
+  std::shared_ptr<LocalTransportHandle> local_transport_handle_ = std::make_shared<LocalTransportHandle>();
+
+ public:
+  Io<LocalTransport> Register(Address address) {
+    LocalTransport local_transport(local_transport_handle_);
+    return Io{local_transport, address};
+  }
+
+  void ShutDown() { local_transport_handle_->ShutDown(); }
+};
+
+}  // namespace memgraph::io::local_transport

src/io/local_transport/local_transport.hpp

@@ -0,0 +1,64 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <chrono>
+#include <memory>
+#include <random>
+#include <utility>
+
+#include "io/address.hpp"
+#include "io/local_transport/local_transport_handle.hpp"
+#include "io/time.hpp"
+#include "io/transport.hpp"
+
+namespace memgraph::io::local_transport {
+
+class LocalTransport {
+  std::shared_ptr<LocalTransportHandle> local_transport_handle_;
+
+ public:
+  explicit LocalTransport(std::shared_ptr<LocalTransportHandle> local_transport_handle)
+      : local_transport_handle_(std::move(local_transport_handle)) {}
+
+  template <Message RequestT, Message ResponseT>
+  ResponseFuture<ResponseT> Request(Address to_address, Address from_address, RequestId request_id, RequestT request,
+                                    Duration timeout) {
+    auto [future, promise] = memgraph::io::FuturePromisePair<ResponseResult<ResponseT>>();
+
+    local_transport_handle_->SubmitRequest(to_address, from_address, request_id, std::move(request), timeout,
+                                           std::move(promise));
+
+    return std::move(future);
+  }
+
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) RequestResult<Ms...> Receive(Address receiver_address, Duration timeout) {
+    return local_transport_handle_->template Receive<Ms...>(receiver_address, timeout);
+  }
+
+  template <Message M>
+  void Send(Address to_address, Address from_address, RequestId request_id, M &&message) {
+    return local_transport_handle_->template Send<M>(to_address, from_address, request_id, std::forward<M>(message));
+  }
+
+  Time Now() const { return local_transport_handle_->Now(); }
+
+  bool ShouldShutDown() const { return local_transport_handle_->ShouldShutDown(); }
+
+  template <class D = std::poisson_distribution<>, class Return = uint64_t>
+  Return Rand(D distrib) {
+    std::random_device rng;
+    return distrib(rng);
+  }
+};
+};  // namespace memgraph::io::local_transport

src/io/local_transport/local_transport_handle.hpp

@@ -0,0 +1,151 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <chrono>
+#include <condition_variable>
+#include <iostream>
+#include <map>
+#include <mutex>
+
+#include "io/errors.hpp"
+#include "io/message_conversion.hpp"
+#include "io/time.hpp"
+#include "io/transport.hpp"
+
+namespace memgraph::io::local_transport {
+
+class LocalTransportHandle {
+  mutable std::mutex mu_{};
+  mutable std::condition_variable cv_;
+  bool should_shut_down_ = false;
+
+  // the responses to requests that are being waited on
+  std::map<PromiseKey, DeadlineAndOpaquePromise> promises_;
+
+  // messages that are sent to servers that may later receive them
+  std::vector<OpaqueMessage> can_receive_;
+
+ public:
+  ~LocalTransportHandle() {
+    for (auto &&[pk, promise] : promises_) {
+      std::move(promise.promise).TimeOut();
+    }
+    promises_.clear();
+  }
+
+  void ShutDown() {
+    std::unique_lock<std::mutex> lock(mu_);
+    should_shut_down_ = true;
+    cv_.notify_all();
+  }
+
+  bool ShouldShutDown() const {
+    std::unique_lock<std::mutex> lock(mu_);
+    return should_shut_down_;
+  }
+
+  static Time Now() {
+    auto nano_time = std::chrono::system_clock::now();
+    return std::chrono::time_point_cast<std::chrono::microseconds>(nano_time);
+  }
+
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) RequestResult<Ms...> Receive(Address /* receiver_address */, Duration timeout) {
+    std::unique_lock lock(mu_);
+
+    Time before = Now();
+
+    spdlog::info("can_receive_ size: {}", can_receive_.size());
+
+    while (can_receive_.empty()) {
+      Time now = Now();
+
+      // protection against non-monotonic timesources
+      auto maxed_now = std::max(now, before);
+      auto elapsed = maxed_now - before;
+
+      if (timeout < elapsed) {
+        return TimedOut{};
+      }
+
+      Duration relative_timeout = timeout - elapsed;
+
+      std::cv_status cv_status_value = cv_.wait_for(lock, relative_timeout);
+
+      if (cv_status_value == std::cv_status::timeout) {
+        return TimedOut{};
+      }
+    }
+
+    auto current_message = std::move(can_receive_.back());
+    can_receive_.pop_back();
+
+    auto m_opt = std::move(current_message).Take<Ms...>();
+
+    return std::move(m_opt).value();
+  }
+
+  template <Message M>
+  void Send(Address to_address, Address from_address, RequestId request_id, M &&message) {
+    std::any message_any(std::forward<M>(message));
+    OpaqueMessage opaque_message{.to_address = to_address,
+                                 .from_address = from_address,
+                                 .request_id = request_id,
+                                 .message = std::move(message_any)};
+
+    PromiseKey promise_key{
+        .requester_address = to_address, .request_id = opaque_message.request_id, .replier_address = from_address};
+
+    {
+      std::unique_lock<std::mutex> lock(mu_);
+
+      if (promises_.contains(promise_key)) {
+        spdlog::info("using message to fill promise");
+        // complete waiting promise if it's there
+        DeadlineAndOpaquePromise dop = std::move(promises_.at(promise_key));
+        promises_.erase(promise_key);
+
+        dop.promise.Fill(std::move(opaque_message));
+      } else {
+        spdlog::info("placing message in can_receive_");
+        can_receive_.emplace_back(std::move(opaque_message));
+      }
+    }  // lock dropped
+
+    cv_.notify_all();
+  }
+
+  template <Message RequestT, Message ResponseT>
+  void SubmitRequest(Address to_address, Address from_address, RequestId request_id, RequestT &&request,
+                     Duration timeout, ResponsePromise<ResponseT> promise) {
+    const bool port_matches = to_address.last_known_port == from_address.last_known_port;
+    const bool ip_matches = to_address.last_known_ip == from_address.last_known_ip;
+
+    MG_ASSERT(port_matches && ip_matches);
+    const Time deadline = Now() + timeout;
+
+    {
+      std::unique_lock<std::mutex> lock(mu_);
+
+      PromiseKey promise_key{
+          .requester_address = from_address, .request_id = request_id, .replier_address = to_address};
+      OpaquePromise opaque_promise(std::move(promise).ToUnique());
+      DeadlineAndOpaquePromise dop{.deadline = deadline, .promise = std::move(opaque_promise)};
+      promises_.emplace(std::move(promise_key), std::move(dop));
+    }  // lock dropped
+
+    Send(to_address, from_address, request_id, std::forward<RequestT>(request));
+  }
+};
+
+}  // namespace memgraph::io::local_transport

src/io/message_conversion.hpp

@@ -0,0 +1,232 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "io/transport.hpp"
+
+namespace memgraph::io {
+
+using memgraph::io::Duration;
+using memgraph::io::Message;
+using memgraph::io::Time;
+
+struct PromiseKey {
+  Address requester_address;
+  uint64_t request_id;
+  // TODO(tyler) possibly remove replier_address from promise key
+  // once we want to support DSR.
+  Address replier_address;
+
+ public:
+  friend bool operator<(const PromiseKey &lhs, const PromiseKey &rhs) {
+    if (lhs.requester_address != rhs.requester_address) {
+      return lhs.requester_address < rhs.requester_address;
+    }
+
+    if (lhs.request_id != rhs.request_id) {
+      return lhs.request_id < rhs.request_id;
+    }
+
+    return lhs.replier_address < rhs.replier_address;
+  }
+};
+
+struct OpaqueMessage {
+  Address to_address;
+  Address from_address;
+  uint64_t request_id;
+  std::any message;
+
+  /// Recursively tries to match a specific type from the outer
+  /// variant's parameter pack against the type of the std::any,
+  /// and if it matches, make it concrete and return it. Otherwise,
+  /// move on and compare the any with the next type from the
+  /// parameter pack.
+  ///
+  /// Return is the full std::variant<Ts...> type that holds the
+  /// full parameter pack without interfering with recursive
+  /// narrowing expansion.
+  template <typename Return, Message Head, Message... Rest>
+  std::optional<Return> Unpack(std::any &&a) {
+    if (typeid(Head) == a.type()) {
+      Head concrete = std::any_cast<Head>(std::move(a));
+      return concrete;
+    }
+
+    if constexpr (sizeof...(Rest) > 0) {
+      return Unpack<Return, Rest...>(std::move(a));
+    } else {
+      return std::nullopt;
+    }
+  }
+
+  /// High level "user-facing" conversion function that lets
+  /// people interested in conversion only supply a single
+  /// parameter pack for the types that they want to compare
+  /// with the any and potentially include in the returned
+  /// variant.
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) std::optional<std::variant<Ms...>> VariantFromAny(std::any &&a) {
+    return Unpack<std::variant<Ms...>, Ms...>(std::move(a));
+  }
+
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) std::optional<RequestEnvelope<Ms...>> Take() && {
+    std::optional<std::variant<Ms...>> m_opt = VariantFromAny<Ms...>(std::move(message));
+
+    if (m_opt) {
+      return RequestEnvelope<Ms...>{
+          .message = std::move(*m_opt),
+          .request_id = request_id,
+          .to_address = to_address,
+          .from_address = from_address,
+      };
+    }
+
+    return std::nullopt;
+  }
+};
+
+class OpaquePromiseTraitBase {
+ public:
+  virtual const std::type_info *TypeInfo() const = 0;
+  virtual bool IsAwaited(void *ptr) const = 0;
+  virtual void Fill(void *ptr, OpaqueMessage &&) const = 0;
+  virtual void TimeOut(void *ptr) const = 0;
+
+  virtual ~OpaquePromiseTraitBase() = default;
+  OpaquePromiseTraitBase() = default;
+  OpaquePromiseTraitBase(const OpaquePromiseTraitBase &) = delete;
+  OpaquePromiseTraitBase &operator=(const OpaquePromiseTraitBase &) = delete;
+  OpaquePromiseTraitBase(OpaquePromiseTraitBase &&old) = delete;
+  OpaquePromiseTraitBase &operator=(OpaquePromiseTraitBase &&) = delete;
+};
+
+template <typename T>
+class OpaquePromiseTrait : public OpaquePromiseTraitBase {
+ public:
+  const std::type_info *TypeInfo() const override { return &typeid(T); };
+
+  bool IsAwaited(void *ptr) const override { return static_cast<ResponsePromise<T> *>(ptr)->IsAwaited(); };
+
+  void Fill(void *ptr, OpaqueMessage &&opaque_message) const override {
+    T message = std::any_cast<T>(std::move(opaque_message.message));
+    auto response_envelope = ResponseEnvelope<T>{.message = std::move(message),
+                                                 .request_id = opaque_message.request_id,
+                                                 .to_address = opaque_message.to_address,
+                                                 .from_address = opaque_message.from_address};
+    auto promise = static_cast<ResponsePromise<T> *>(ptr);
+    auto unique_promise = std::unique_ptr<ResponsePromise<T>>(promise);
+    unique_promise->Fill(std::move(response_envelope));
+  };
+
+  void TimeOut(void *ptr) const override {
+    auto promise = static_cast<ResponsePromise<T> *>(ptr);
+    auto unique_promise = std::unique_ptr<ResponsePromise<T>>(promise);
+    ResponseResult<T> result = TimedOut{};
+    unique_promise->Fill(std::move(result));
+  }
+};
+
+class OpaquePromise {
+  void *ptr_;
+  std::unique_ptr<OpaquePromiseTraitBase> trait_;
+
+ public:
+  OpaquePromise(OpaquePromise &&old) noexcept : ptr_(old.ptr_), trait_(std::move(old.trait_)) {
+    MG_ASSERT(old.ptr_ != nullptr);
+    old.ptr_ = nullptr;
+  }
+
+  OpaquePromise &operator=(OpaquePromise &&old) noexcept {
+    MG_ASSERT(ptr_ == nullptr);
+    MG_ASSERT(old.ptr_ != nullptr);
+    MG_ASSERT(this != &old);
+    ptr_ = old.ptr_;
+    trait_ = std::move(old.trait_);
+    old.ptr_ = nullptr;
+    return *this;
+  }
+
+  OpaquePromise(const OpaquePromise &) = delete;
+  OpaquePromise &operator=(const OpaquePromise &) = delete;
+
+  template <typename T>
+  std::unique_ptr<ResponsePromise<T>> Take() && {
+    MG_ASSERT(typeid(T) == *trait_->TypeInfo());
+    MG_ASSERT(ptr_ != nullptr);
+
+    auto ptr = static_cast<ResponsePromise<T> *>(ptr_);
+
+    ptr_ = nullptr;
+
+    return std::unique_ptr<T>(ptr);
+  }
+
+  template <typename T>
+  explicit OpaquePromise(std::unique_ptr<ResponsePromise<T>> promise)
+      : ptr_(static_cast<void *>(promise.release())), trait_(std::make_unique<OpaquePromiseTrait<T>>()) {}
+
+  bool IsAwaited() {
+    MG_ASSERT(ptr_ != nullptr);
+    return trait_->IsAwaited(ptr_);
+  }
+
+  void TimeOut() {
+    MG_ASSERT(ptr_ != nullptr);
+    trait_->TimeOut(ptr_);
+    ptr_ = nullptr;
+  }
+
+  void Fill(OpaqueMessage &&opaque_message) {
+    MG_ASSERT(ptr_ != nullptr);
+    trait_->Fill(ptr_, std::move(opaque_message));
+    ptr_ = nullptr;
+  }
+
+  ~OpaquePromise() {
+    MG_ASSERT(ptr_ == nullptr, "OpaquePromise destroyed without being explicitly timed out or filled");
+  }
+};
+
+struct DeadlineAndOpaquePromise {
+  Time deadline;
+  OpaquePromise promise;
+};
+
+template <class From>
+std::type_info const &type_info_for_variant(From const &from) {
+  return std::visit([](auto &&x) -> decltype(auto) { return typeid(x); }, from);
+}
+
+template <typename From, typename Return, typename Head, typename... Rest>
+std::optional<Return> ConvertVariantInner(From &&a) {
+  if (typeid(Head) == type_info_for_variant(a)) {
+    Head concrete = std::get<Head>(std::forward<From>(a));
+    return concrete;
+  }
+
+  if constexpr (sizeof...(Rest) > 0) {
+    return ConvertVariantInner<From, Return, Rest...>(std::forward<From>(a));
+  } else {
+    return std::nullopt;
+  }
+}
+
+/// This function converts a variant to another variant holding a subset OR superset of
+/// possible types.
+template <class From, class... Ms>
+requires(sizeof...(Ms) > 0) std::optional<std::variant<Ms...>> ConvertVariant(From &&from) {
+  return ConvertVariantInner<From, std::variant<Ms...>, Ms...>(std::forward<From>(from));
+}
+
+}  // namespace memgraph::io

src/io/messages.hpp

@@ -0,0 +1,46 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <variant>
+
+#include <coordinator/coordinator.hpp>
+#include <io/rsm/raft.hpp>
+#include "query/v2/requests.hpp"
+#include "utils/concepts.hpp"
+
+namespace memgraph::io::messages {
+
+using memgraph::coordinator::CoordinatorReadRequests;
+using memgraph::coordinator::CoordinatorWriteRequests;
+using memgraph::coordinator::CoordinatorWriteResponses;
+using StorageReadRequest = msgs::ReadRequests;
+using StorageWriteRequest = msgs::WriteRequests;
+
+using memgraph::io::rsm::AppendRequest;
+using memgraph::io::rsm::AppendResponse;
+using memgraph::io::rsm::ReadRequest;
+using memgraph::io::rsm::VoteRequest;
+using memgraph::io::rsm::VoteResponse;
+using memgraph::io::rsm::WriteRequest;
+using memgraph::io::rsm::WriteResponse;
+
+using CoordinatorMessages =
+    std::variant<ReadRequest<CoordinatorReadRequests>, AppendRequest<CoordinatorWriteRequests>, AppendResponse,
+                 WriteRequest<CoordinatorWriteRequests>, VoteRequest, VoteResponse>;
+
+using ShardMessages = std::variant<ReadRequest<StorageReadRequest>, AppendRequest<StorageWriteRequest>, AppendResponse,
+                                   WriteRequest<StorageWriteRequest>, VoteRequest, VoteResponse>;
+
+using ShardManagerMessages = std::variant<WriteResponse<CoordinatorWriteResponses>>;
+
+}  // namespace memgraph::io::messages

src/io/rsm/raft.hpp

@@ -0,0 +1,926 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+// TODO(tyler) buffer out-of-order Append buffers on the Followers to reassemble more quickly
+// TODO(tyler) handle granular batch sizes based on simple flow control
+
+#pragma once
+
+#include <deque>
+#include <iostream>
+#include <map>
+#include <set>
+#include <thread>
+#include <unordered_map>
+#include <vector>
+
+#include "io/simulator/simulator.hpp"
+#include "io/transport.hpp"
+#include "utils/concepts.hpp"
+
+namespace memgraph::io::rsm {
+
+/// Timeout and replication tunables
+using namespace std::chrono_literals;
+static constexpr auto kMinimumElectionTimeout = 100ms;
+static constexpr auto kMaximumElectionTimeout = 200ms;
+static constexpr auto kMinimumBroadcastTimeout = 40ms;
+static constexpr auto kMaximumBroadcastTimeout = 60ms;
+static constexpr auto kMinimumCronInterval = 1ms;
+static constexpr auto kMaximumCronInterval = 2ms;
+static constexpr auto kMinimumReceiveTimeout = 40ms;
+static constexpr auto kMaximumReceiveTimeout = 60ms;
+static_assert(kMinimumElectionTimeout > kMaximumBroadcastTimeout,
+              "The broadcast timeout has to be smaller than the election timeout!");
+static_assert(kMinimumElectionTimeout < kMaximumElectionTimeout,
+              "The minimum election timeout has to be smaller than the maximum election timeout!");
+static_assert(kMinimumBroadcastTimeout < kMaximumBroadcastTimeout,
+              "The minimum broadcast timeout has to be smaller than the maximum broadcast timeout!");
+static_assert(kMinimumCronInterval < kMaximumCronInterval,
+              "The minimum cron interval has to be smaller than the maximum cron interval!");
+static_assert(kMinimumReceiveTimeout < kMaximumReceiveTimeout,
+              "The minimum receive timeout has to be smaller than the maximum receive timeout!");
+static constexpr size_t kMaximumAppendBatchSize = 1024;
+
+using Term = uint64_t;
+using LogIndex = uint64_t;
+using LogSize = uint64_t;
+
+template <typename WriteOperation>
+struct WriteRequest {
+  WriteOperation operation;
+};
+
+/// WriteResponse is returned to a client after
+/// their WriteRequest was entered in to the raft
+/// log and it reached consensus.
+///
+/// WriteReturn is the result of applying the WriteRequest to
+/// ReplicatedState, and if the ReplicatedState::write
+/// method is deterministic, all replicas will
+/// have the same ReplicatedState after applying
+/// the submitted WriteRequest.
+template <typename WriteReturn>
+struct WriteResponse {
+  bool success;
+  WriteReturn write_return;
+  std::optional<Address> retry_leader;
+  LogIndex raft_index;
+};
+
+template <typename ReadOperation>
+struct ReadRequest {
+  ReadOperation operation;
+};
+
+template <typename ReadReturn>
+struct ReadResponse {
+  bool success;
+  ReadReturn read_return;
+  std::optional<Address> retry_leader;
+};
+
+/// AppendRequest is a raft-level message that the Leader
+/// periodically broadcasts to all Follower peers. This
+/// serves three main roles:
+/// 1. acts as a heartbeat from the Leader to the Follower
+/// 2. replicates new data that the Leader has received to the Follower
+/// 3. informs Follower peers when the commit index has increased,
+///    signalling that it is now safe to apply log items to the
+///    replicated state machine
+template <typename WriteRequest>
+struct AppendRequest {
+  Term term = 0;
+  LogIndex batch_start_log_index;
+  Term last_log_term;
+  std::vector<std::pair<Term, WriteRequest>> entries;
+  LogSize leader_commit;
+};
+
+struct AppendResponse {
+  bool success;
+  Term term;
+  Term last_log_term;
+  // a small optimization over the raft paper, tells
+  // the leader the offset that we are interested in
+  // to send log offsets from for us. This will only
+  // be useful at the beginning of a leader's term.
+  LogSize log_size;
+};
+
+struct VoteRequest {
+  Term term = 0;
+  LogSize log_size;
+  Term last_log_term;
+};
+
+struct VoteResponse {
+  Term term = 0;
+  LogSize committed_log_size;
+  bool vote_granted = false;
+};
+
+template <typename WriteRequest>
+struct CommonState {
+  Term term = 0;
+  std::vector<std::pair<Term, WriteRequest>> log;
+  LogSize committed_log_size = 0;
+  LogSize applied_size = 0;
+};
+
+struct FollowerTracker {
+  LogIndex next_index = 0;
+  LogSize confirmed_log_size = 0;
+};
+
+struct PendingClientRequest {
+  RequestId request_id;
+  Address address;
+  Time received_at;
+};
+
+struct Leader {
+  std::map<Address, FollowerTracker> followers;
+  std::unordered_map<LogIndex, PendingClientRequest> pending_client_requests;
+  Time last_broadcast = Time::min();
+
+  std::string static ToString() { return "\tLeader   \t"; }
+};
+
+struct Candidate {
+  std::map<Address, LogSize> successful_votes;
+  Time election_began = Time::min();
+  std::set<Address> outstanding_votes;
+
+  std::string static ToString() { return "\tCandidate\t"; }
+};
+
+struct Follower {
+  Time last_received_append_entries_timestamp;
+  Address leader_address;
+
+  std::string static ToString() { return "\tFollower \t"; }
+};
+
+using Role = std::variant<Candidate, Leader, Follower>;
+
+template <typename Role>
+concept AllRoles = memgraph::utils::SameAsAnyOf<Role, Leader, Follower, Candidate>;
+
+template <typename Role>
+concept LeaderOrFollower = memgraph::utils::SameAsAnyOf<Role, Leader, Follower>;
+
+template <typename Role>
+concept FollowerOrCandidate = memgraph::utils::SameAsAnyOf<Role, Follower, Candidate>;
+
+/*
+all ReplicatedState classes should have an Apply method
+that returns our WriteResponseValue after consensus, and
+a Read method that returns our ReadResponseValue without
+requiring consensus.
+
+ReadResponse Read(ReadOperation);
+WriteResponseValue ReplicatedState::Apply(WriteRequest);
+
+For example:
+If the state is uint64_t, and WriteRequest is `struct PlusOne {};`,
+and WriteResponseValue is also uint64_t (the new value), then
+each call to state.Apply(PlusOne{}) will return the new value
+after incrementing it. 0, 1, 2, 3... and this will be sent back
+to the client that requested the mutation.
+
+In practice, these mutations will usually be predicated on some
+previous value, so that they are idempotent, functioning similarly
+to a CAS operation.
+*/
+template <typename WriteOperation, typename ReadOperation, typename ReplicatedState, typename WriteResponseValue,
+          typename ReadResponseValue>
+concept Rsm = requires(ReplicatedState state, WriteOperation w, ReadOperation r) {
+  { state.Read(r) } -> std::same_as<ReadResponseValue>;
+  { state.Apply(w) } -> std::same_as<WriteResponseValue>;
+};
+
+/// Parameter           Purpose
+/// --------------------------
+/// IoImpl              the concrete Io provider - SimulatorTransport, ThriftTransport, etc...
+/// ReplicatedState     the high-level data structure that is managed by the raft-backed replicated state machine
+/// WriteOperation      the individual operation type that is applied to the ReplicatedState in identical order
+///                     across each replica
+/// WriteResponseValue  the return value of calling ReplicatedState::Apply(WriteOperation), which is executed in
+///                     identical order across all replicas after an WriteOperation reaches consensus.
+/// ReadOperation       the type of operations that do not require consensus before executing directly
+///                     on a const ReplicatedState &
+/// ReadResponseValue   the return value of calling ReplicatedState::Read(ReadOperation), which is executed directly
+///                     without going through consensus first
+template <typename IoImpl, typename ReplicatedState, typename WriteOperation, typename WriteResponseValue,
+          typename ReadOperation, typename ReadResponseValue>
+requires Rsm<WriteOperation, ReadOperation, ReplicatedState, WriteResponseValue, ReadResponseValue>
+class Raft {
+  CommonState<WriteOperation> state_;
+  Role role_ = Candidate{};
+  Io<IoImpl> io_;
+  std::vector<Address> peers_;
+  ReplicatedState replicated_state_;
+  Time next_cron_;
+
+ public:
+  Raft(Io<IoImpl> &&io, std::vector<Address> peers, ReplicatedState &&replicated_state)
+      : io_(std::forward<Io<IoImpl>>(io)),
+        peers_(peers),
+        replicated_state_(std::forward<ReplicatedState>(replicated_state)) {
+    if (peers.empty()) {
+      role_ = Leader{};
+    }
+  }
+
+  /// Periodic protocol maintenance. Returns the time that Cron should be called again
+  /// in the future.
+  Time Cron() {
+    // dispatch periodic logic based on our role to a specific Cron method.
+    std::optional<Role> new_role = std::visit([&](auto &role) { return Cron(role); }, role_);
+
+    if (new_role) {
+      role_ = std::move(new_role).value();
+    }
+    const Duration random_cron_interval = RandomTimeout(kMinimumCronInterval, kMaximumCronInterval);
+
+    return io_.Now() + random_cron_interval;
+  }
+
+  /// Returns the Address for our underlying Io implementation
+  Address GetAddress() { return io_.GetAddress(); }
+
+  using ReceiveVariant = std::variant<ReadRequest<ReadOperation>, AppendRequest<WriteOperation>, AppendResponse,
+                                      WriteRequest<WriteOperation>, VoteRequest, VoteResponse>;
+
+  void Handle(ReceiveVariant &&message_variant, RequestId request_id, Address from_address) {
+    // dispatch the message to a handler based on our role,
+    // which can be specified in the Handle first argument,
+    // or it can be `auto` if it's a handler for several roles
+    // or messages.
+    std::optional<Role> new_role = std::visit(
+        [&](auto &&msg, auto &role) mutable {
+          return Handle(role, std::forward<decltype(msg)>(msg), request_id, from_address);
+        },
+        std::forward<ReceiveVariant>(message_variant), role_);
+
+    // TODO(tyler) (M3) maybe replace std::visit with get_if for explicit prioritized matching, [[likely]] etc...
+    if (new_role) {
+      role_ = std::move(new_role).value();
+    }
+  }
+
+  void Run() {
+    while (!io_.ShouldShutDown()) {
+      const auto now = io_.Now();
+      if (now >= next_cron_) {
+        next_cron_ = Cron();
+      }
+
+      const Duration receive_timeout = RandomTimeout(kMinimumReceiveTimeout, kMaximumReceiveTimeout);
+
+      auto request_result =
+          io_.template ReceiveWithTimeout<ReadRequest<ReadOperation>, AppendRequest<WriteOperation>, AppendResponse,
+                                          WriteRequest<WriteOperation>, VoteRequest, VoteResponse>(receive_timeout);
+      if (request_result.HasError()) {
+        continue;
+      }
+
+      auto request = std::move(request_result.GetValue());
+
+      Handle(std::move(request.message), request.request_id, request.from_address);
+    }
+  }
+
+ private:
+  // Raft paper - 5.3
+  // When the entry has been safely replicated, the leader applies the
+  // entry to its state machine and returns the result of that
+  // execution to the client.
+  //
+  // "Safely replicated" is defined as being known to be present
+  // on at least a majority of all peers (inclusive of the Leader).
+  void BumpCommitIndexAndReplyToClients(Leader &leader) {
+    auto confirmed_log_sizes = std::vector<LogSize>{};
+
+    // We include our own log size in the calculation of the log
+    // confirmed log size that is present on at least a majority of all peers.
+    confirmed_log_sizes.push_back(state_.log.size());
+
+    for (const auto &[addr, f] : leader.followers) {
+      confirmed_log_sizes.push_back(f.confirmed_log_size);
+      Log("Follower at port ", addr.last_known_port, " has confirmed log size of: ", f.confirmed_log_size);
+    }
+
+    // reverse sort from highest to lowest (using std::ranges::greater)
+    std::ranges::sort(confirmed_log_sizes, std::ranges::greater());
+
+    // This is a particularly correctness-critical calculation because it
+    // determines the committed log size that will be broadcast in
+    // the next AppendRequest.
+    //
+    // If the following sizes are recorded for clusters of different numbers of peers,
+    // these are the expected sizes that are considered to have reached consensus:
+    //
+    // state           | expected value | (confirmed_log_sizes.size() / 2)
+    // [1]              1                 (1 / 2) => 0
+    // [2, 1]           1                 (2 / 2) => 1
+    // [3, 2, 1]        2                 (3 / 2) => 1
+    // [4, 3, 2, 1]     2                 (4 / 2) => 2
+    // [5, 4, 3, 2, 1]  3                 (5 / 2) => 2
+    const size_t majority_index = confirmed_log_sizes.size() / 2;
+    const LogSize new_committed_log_size = confirmed_log_sizes[majority_index];
+
+    // We never go backwards in history.
+    MG_ASSERT(state_.committed_log_size <= new_committed_log_size,
+              "as a Leader, we have previously set our committed_log_size to {}, but our Followers have a majority "
+              "committed_log_size of {}",
+              state_.committed_log_size, new_committed_log_size);
+
+    state_.committed_log_size = new_committed_log_size;
+
+    // For each size between the old size and the new one (inclusive),
+    // Apply that log's WriteOperation to our replicated_state_,
+    // and use the specific return value of the ReplicatedState::Apply
+    // method (WriteResponseValue) to respond to the requester.
+    for (; state_.applied_size < state_.committed_log_size; state_.applied_size++) {
+      const LogIndex apply_index = state_.applied_size;
+      const auto &write_request = state_.log[apply_index].second;
+      const WriteResponseValue write_return = replicated_state_.Apply(write_request);
+
+      if (leader.pending_client_requests.contains(apply_index)) {
+        const PendingClientRequest client_request = std::move(leader.pending_client_requests.at(apply_index));
+        leader.pending_client_requests.erase(apply_index);
+
+        const WriteResponse<WriteResponseValue> resp{
+            .success = true,
+            .write_return = std::move(write_return),
+            .raft_index = apply_index,
+        };
+
+        io_.Send(client_request.address, client_request.request_id, std::move(resp));
+      }
+    }
+
+    Log("committed_log_size is now ", state_.committed_log_size);
+  }
+
+  // Raft paper - 5.1
+  // AppendEntries RPCs are initiated by leaders to replicate log entries and to provide a form of heartbeat
+  void BroadcastAppendEntries(std::map<Address, FollowerTracker> &followers) {
+    for (auto &[address, follower] : followers) {
+      const LogIndex next_index = follower.next_index;
+
+      const auto missing = state_.log.size() - next_index;
+      const auto batch_size = std::min(missing, kMaximumAppendBatchSize);
+      const auto start_index = next_index;
+      const auto end_index = start_index + batch_size;
+
+      // advance follower's next index
+      follower.next_index += batch_size;
+
+      std::vector<std::pair<Term, WriteOperation>> entries;
+
+      entries.insert(entries.begin(), state_.log.begin() + start_index, state_.log.begin() + end_index);
+
+      const Term previous_term_from_index = PreviousTermFromIndex(start_index);
+
+      Log("sending ", entries.size(), " entries to Follower ", address.last_known_port,
+          " which are above its next_index of ", next_index);
+
+      AppendRequest<WriteOperation> ar{
+          .term = state_.term,
+          .batch_start_log_index = start_index,
+          .last_log_term = previous_term_from_index,
+          .entries = std::move(entries),
+          .leader_commit = state_.committed_log_size,
+      };
+
+      // request_id not necessary to set because it's not a Future-backed Request.
+      static constexpr RequestId request_id = 0;
+
+      io_.Send(address, request_id, std::move(ar));
+    }
+  }
+
+  // Raft paper - 5.2
+  // Raft uses randomized election timeouts to ensure that split votes are rare and that they are resolved quickly
+  Duration RandomTimeout(Duration min, Duration max) {
+    std::uniform_int_distribution time_distrib(min.count(), max.count());
+
+    const auto rand_micros = io_.Rand(time_distrib);
+
+    return Duration{rand_micros};
+  }
+
+  Duration RandomTimeout(int min_micros, int max_micros) {
+    std::uniform_int_distribution time_distrib(min_micros, max_micros);
+
+    const int rand_micros = io_.Rand(time_distrib);
+
+    return std::chrono::microseconds{rand_micros};
+  }
+
+  Term PreviousTermFromIndex(LogIndex index) const {
+    if (index == 0 || state_.log.size() + 1 <= index) {
+      return 0;
+    }
+
+    const auto &[term, data] = state_.log.at(index - 1);
+    return term;
+  }
+
+  Term CommittedLogTerm() {
+    MG_ASSERT(state_.log.size() >= state_.committed_log_size);
+    if (state_.log.empty() || state_.committed_log_size == 0) {
+      return 0;
+    }
+
+    const auto &[term, data] = state_.log.at(state_.committed_log_size - 1);
+    return term;
+  }
+
+  Term LastLogTerm() const {
+    if (state_.log.empty()) {
+      return 0;
+    }
+
+    const auto &[term, data] = state_.log.back();
+    return term;
+  }
+
+  template <typename... Ts>
+  void Log(Ts &&...args) {
+    const Time now = io_.Now();
+    const auto micros = std::chrono::duration_cast<std::chrono::milliseconds>(now.time_since_epoch()).count();
+    const Term term = state_.term;
+    const std::string role_string = std::visit([&](const auto &role) { return role.ToString(); }, role_);
+
+    std::ostringstream out;
+
+    out << '\t' << static_cast<int>(micros) << "\t" << term << "\t" << io_.GetAddress().last_known_port;
+
+    out << role_string;
+
+    (out << ... << args);
+
+    spdlog::info(out.str());
+  }
+
+  /////////////////////////////////////////////////////////////
+  /// Raft-related Cron methods
+  ///
+  /// Cron + std::visit is how events are dispatched
+  /// to certain code based on Raft role.
+  ///
+  /// Cron(role) takes as the first argument a reference to its
+  /// role, and as the second argument, the message that has
+  /// been received.
+  /////////////////////////////////////////////////////////////
+
+  // Raft paper - 5.2
+  // Candidates keep sending Vote to peers until:
+  // 1. receiving Append with a higher term (become Follower)
+  // 2. receiving Vote with a higher term (become a Follower)
+  // 3. receiving a quorum of responses to our last batch of Vote (become a Leader)
+  std::optional<Role> Cron(Candidate &candidate) {
+    const auto now = io_.Now();
+    const Duration election_timeout = RandomTimeout(kMinimumElectionTimeout, kMaximumElectionTimeout);
+    const auto election_timeout_us = std::chrono::duration_cast<std::chrono::milliseconds>(election_timeout).count();
+
+    if (now - candidate.election_began > election_timeout) {
+      state_.term++;
+      Log("becoming Candidate for term ", state_.term, " after leader timeout of ", election_timeout_us,
+          "ms elapsed since last election attempt");
+
+      const VoteRequest request{
+          .term = state_.term,
+          .log_size = state_.log.size(),
+          .last_log_term = LastLogTerm(),
+      };
+
+      auto outstanding_votes = std::set<Address>();
+
+      for (const auto &peer : peers_) {
+        // request_id not necessary to set because it's not a Future-backed Request.
+        static constexpr auto request_id = 0;
+        io_.template Send<VoteRequest>(peer, request_id, request);
+        outstanding_votes.insert(peer);
+      }
+
+      return Candidate{
+          .successful_votes = std::map<Address, LogIndex>(),
+          .election_began = now,
+          .outstanding_votes = outstanding_votes,
+      };
+    }
+    return std::nullopt;
+  }
+
+  // Raft paper - 5.2
+  // Followers become candidates if we haven't heard from the leader
+  // after a randomized timeout.
+  std::optional<Role> Cron(Follower &follower) {
+    const auto now = io_.Now();
+    const auto time_since_last_append_entries = now - follower.last_received_append_entries_timestamp;
+
+    // randomized follower timeout
+    const Duration election_timeout = RandomTimeout(kMinimumElectionTimeout, kMaximumElectionTimeout);
+
+    if (time_since_last_append_entries > election_timeout) {
+      // become a Candidate if we haven't heard from the Leader after this timeout
+      return Candidate{};
+    }
+
+    return std::nullopt;
+  }
+
+  // Leaders (re)send AppendRequest to followers.
+  std::optional<Role> Cron(Leader &leader) {
+    const Time now = io_.Now();
+    const Duration broadcast_timeout = RandomTimeout(kMinimumBroadcastTimeout, kMaximumBroadcastTimeout);
+
+    if (now - leader.last_broadcast > broadcast_timeout) {
+      BroadcastAppendEntries(leader.followers);
+      leader.last_broadcast = now;
+    }
+
+    return std::nullopt;
+  }
+
+  /////////////////////////////////////////////////////////////
+  /// Raft-related Handle methods
+  ///
+  /// Handle + std::visit is how events are dispatched
+  /// to certain code based on Raft role.
+  ///
+  /// Handle(role, message, ...)
+  /// takes as the first argument a reference
+  /// to its role, and as the second argument, the
+  /// message that has been received.
+  /////////////////////////////////////////////////////////////
+
+  // all roles can receive Vote and possibly become a follower
+  template <AllRoles ALL>
+  std::optional<Role> Handle(ALL & /* variable */, VoteRequest &&req, RequestId request_id, Address from_address) {
+    Log("received VoteRequest from ", from_address.last_known_port, " with term ", req.term);
+    const bool last_log_term_dominates = req.last_log_term >= LastLogTerm();
+    const bool term_dominates = req.term > state_.term;
+    const bool log_size_dominates = req.log_size >= state_.log.size();
+    const bool new_leader = last_log_term_dominates && term_dominates && log_size_dominates;
+
+    if (new_leader) {
+      MG_ASSERT(req.term > state_.term);
+      MG_ASSERT(std::max(req.term, state_.term) == req.term);
+    }
+
+    const VoteResponse res{
+        .term = std::max(req.term, state_.term),
+        .committed_log_size = state_.committed_log_size,
+        .vote_granted = new_leader,
+    };
+
+    io_.Send(from_address, request_id, res);
+
+    if (new_leader) {
+      // become a follower
+      state_.term = req.term;
+      return Follower{
+          .last_received_append_entries_timestamp = io_.Now(),
+          .leader_address = from_address,
+      };
+    }
+
+    if (term_dominates) {
+      Log("received a vote from an inferior candidate. Becoming Candidate");
+      state_.term = std::max(state_.term, req.term) + 1;
+      return Candidate{};
+    }
+
+    return std::nullopt;
+  }
+
+  std::optional<Role> Handle(Candidate &candidate, VoteResponse &&res, RequestId /* variable */, Address from_address) {
+    Log("received VoteResponse");
+
+    if (!res.vote_granted || res.term != state_.term) {
+      Log("received unsuccessful VoteResponse from term ", res.term, " when our candidacy term is ", state_.term);
+      // we received a delayed VoteResponse from the past, which has to do with an election that is
+      // no longer valid. We can simply drop this.
+      return std::nullopt;
+    }
+
+    MG_ASSERT(candidate.outstanding_votes.contains(from_address),
+              "Received unexpected VoteResponse from server not present in Candidate's outstanding_votes!");
+    candidate.outstanding_votes.erase(from_address);
+
+    MG_ASSERT(!candidate.successful_votes.contains(from_address),
+              "Received unexpected VoteResponse from server already in Candidate's successful_votes!");
+    candidate.successful_votes.insert({from_address, res.committed_log_size});
+
+    if (candidate.successful_votes.size() >= candidate.outstanding_votes.size()) {
+      std::map<Address, FollowerTracker> followers{};
+
+      for (const auto &[address, committed_log_size] : candidate.successful_votes) {
+        FollowerTracker follower{
+            .next_index = committed_log_size,
+            .confirmed_log_size = committed_log_size,
+        };
+        followers.insert({address, follower});
+      }
+      for (const auto &address : candidate.outstanding_votes) {
+        FollowerTracker follower{
+            .next_index = state_.log.size(),
+            .confirmed_log_size = 0,
+        };
+        followers.insert({address, follower});
+      }
+
+      Log("becoming Leader at term ", state_.term);
+
+      BroadcastAppendEntries(followers);
+
+      return Leader{
+          .followers = std::move(followers),
+          .pending_client_requests = std::unordered_map<LogIndex, PendingClientRequest>(),
+      };
+    }
+
+    return std::nullopt;
+  }
+
+  template <LeaderOrFollower LOF>
+  std::optional<Role> Handle(LOF & /* variable */, VoteResponse && /* variable */, RequestId /* variable */,
+                             Address /* variable */) {
+    Log("non-Candidate received VoteResponse");
+    return std::nullopt;
+  }
+
+  template <AllRoles ALL>
+  std::optional<Role> Handle(ALL &role, AppendRequest<WriteOperation> &&req, RequestId request_id,
+                             Address from_address) {
+    // log size starts out as state_.committed_log_size and only if everything is successful do we
+    // switch it to the log length.
+    AppendResponse res{
+        .success = false,
+        .term = state_.term,
+        .last_log_term = CommittedLogTerm(),
+        .log_size = state_.log.size(),
+    };
+
+    if constexpr (std::is_same<ALL, Leader>()) {
+      MG_ASSERT(req.term != state_.term, "Multiple leaders are acting under the term ", req.term);
+    }
+
+    const bool is_candidate = std::is_same<ALL, Candidate>();
+    const bool is_failed_competitor = is_candidate && req.term == state_.term;
+    const Time now = io_.Now();
+
+    // Raft paper - 5.2
+    // While waiting for votes, a candidate may receive an
+    // AppendEntries RPC from another server claiming to be leader. If
+    // the leader’s term (included in its RPC) is at least as large as
+    // the candidate’s current term, then the candidate recognizes the
+    // leader as legitimate and returns to follower state.
+    if (req.term > state_.term || is_failed_competitor) {
+      // become follower of this leader, reply with our log status
+      state_.term = req.term;
+
+      io_.Send(from_address, request_id, res);
+
+      Log("becoming Follower of Leader ", from_address.last_known_port, " at term ", req.term);
+      return Follower{
+          .last_received_append_entries_timestamp = now,
+          .leader_address = from_address,
+      };
+    }
+
+    if (req.term < state_.term) {
+      // nack this request from an old leader
+      io_.Send(from_address, request_id, res);
+
+      return std::nullopt;
+    }
+
+    // at this point, we're dealing with our own leader
+    if constexpr (std::is_same<ALL, Follower>()) {
+      // small specialization for when we're already a Follower
+      MG_ASSERT(role.leader_address == from_address, "Multiple Leaders are acting under the same term number!");
+      role.last_received_append_entries_timestamp = now;
+    } else {
+      Log("Somehow entered Follower-specific logic as a non-Follower");
+      MG_ASSERT(false, "Somehow entered Follower-specific logic as a non-Follower");
+    }
+
+    // Handle steady-state conditions.
+    if (req.batch_start_log_index != state_.log.size()) {
+      Log("req.batch_start_log_index of ", req.batch_start_log_index, " does not match our log size of ",
+          state_.log.size());
+    } else if (req.last_log_term != LastLogTerm()) {
+      Log("req.last_log_term differs from our leader term at that slot, expected: ", LastLogTerm(), " but got ",
+          req.last_log_term);
+    } else {
+      // happy path - Apply log
+      Log("applying batch of ", req.entries.size(), " entries to our log starting at index ",
+          req.batch_start_log_index);
+
+      const auto resize_length = req.batch_start_log_index;
+
+      MG_ASSERT(resize_length >= state_.committed_log_size,
+                "Applied history from Leader which goes back in time from our commit_index");
+
+      // possibly chop-off stuff that was replaced by
+      // things with different terms (we got data that
+      // hasn't reached consensus yet, which is normal)
+      state_.log.resize(resize_length);
+
+      if (req.entries.size() > 0) {
+        auto &[first_term, op] = req.entries.at(0);
+        MG_ASSERT(LastLogTerm() <= first_term);
+      }
+
+      state_.log.insert(state_.log.end(), std::make_move_iterator(req.entries.begin()),
+                        std::make_move_iterator(req.entries.end()));
+
+      MG_ASSERT(req.leader_commit >= state_.committed_log_size);
+      state_.committed_log_size = std::min(req.leader_commit, state_.log.size());
+
+      for (; state_.applied_size < state_.committed_log_size; state_.applied_size++) {
+        const auto &write_request = state_.log[state_.applied_size].second;
+        replicated_state_.Apply(write_request);
+      }
+
+      res.success = true;
+    }
+
+    res.last_log_term = LastLogTerm();
+    res.log_size = state_.log.size();
+
+    Log("returning log_size of ", res.log_size);
+
+    io_.Send(from_address, request_id, res);
+
+    return std::nullopt;
+  }
+
+  std::optional<Role> Handle(Leader &leader, AppendResponse &&res, RequestId /* variable */, Address from_address) {
+    if (res.term != state_.term) {
+      Log("received AppendResponse related to a previous term when we (presumably) were the leader");
+      return std::nullopt;
+    }
+
+    // TODO(tyler) when we have dynamic membership, this assert will become incorrect, but we should
+    // keep it in-place until then because it has bug finding value.
+    MG_ASSERT(leader.followers.contains(from_address), "received AppendResponse from unknown Follower");
+
+    // at this point, we know the term matches and we know this Follower
+
+    FollowerTracker &follower = leader.followers.at(from_address);
+
+    if (res.success) {
+      Log("got successful AppendResponse from ", from_address.last_known_port, " with log_size of ", res.log_size);
+      follower.next_index = std::max(follower.next_index, res.log_size);
+    } else {
+      Log("got unsuccessful AppendResponse from ", from_address.last_known_port, " with log_size of ", res.log_size);
+      follower.next_index = res.log_size;
+    }
+
+    follower.confirmed_log_size = std::max(follower.confirmed_log_size, res.log_size);
+
+    BumpCommitIndexAndReplyToClients(leader);
+
+    return std::nullopt;
+  }
+
+  template <FollowerOrCandidate FOC>
+  std::optional<Role> Handle(FOC & /* variable */, AppendResponse && /* variable */, RequestId /* variable */,
+                             Address /* variable */) {
+    // we used to be the leader, and are getting old delayed responses
+    return std::nullopt;
+  }
+
+  /////////////////////////////////////////////////////////////
+  /// RSM-related handle methods
+  /////////////////////////////////////////////////////////////
+
+  // Leaders are able to immediately respond to the requester (with a ReadResponseValue) applied to the ReplicatedState
+  std::optional<Role> Handle(Leader & /* variable */, ReadRequest<ReadOperation> &&req, RequestId request_id,
+                             Address from_address) {
+    Log("handling ReadOperation");
+    ReadOperation read_operation = req.operation;
+
+    ReadResponseValue read_return = replicated_state_.Read(read_operation);
+
+    const ReadResponse<ReadResponseValue> resp{
+        .success = true,
+        .read_return = std::move(read_return),
+        .retry_leader = std::nullopt,
+    };
+
+    io_.Send(from_address, request_id, resp);
+
+    return std::nullopt;
+  }
+
+  // Candidates should respond with a failure, similar to the Candidate + WriteRequest failure below
+  std::optional<Role> Handle(Candidate & /* variable */, ReadRequest<ReadOperation> && /* variable */,
+                             RequestId request_id, Address from_address) {
+    Log("received ReadOperation - not redirecting because no Leader is known");
+    const ReadResponse<ReadResponseValue> res{
+        .success = false,
+    };
+
+    io_.Send(from_address, request_id, res);
+
+    Cron();
+
+    return std::nullopt;
+  }
+
+  // Followers should respond with a redirection, similar to the Follower + WriteRequest response below
+  std::optional<Role> Handle(Follower &follower, ReadRequest<ReadOperation> && /* variable */, RequestId request_id,
+                             Address from_address) {
+    Log("redirecting client to known Leader with port ", follower.leader_address.last_known_port);
+
+    const ReadResponse<ReadResponseValue> res{
+        .success = false,
+        .retry_leader = follower.leader_address,
+    };
+
+    io_.Send(from_address, request_id, res);
+
+    return std::nullopt;
+  }
+
+  // Raft paper - 8
+  // When a client first starts up, it connects to a randomly chosen
+  // server. If the client’s first choice is not the leader, that
+  // server will reject the client’s request and supply information
+  // about the most recent leader it has heard from.
+  std::optional<Role> Handle(Follower &follower, WriteRequest<WriteOperation> && /* variable */, RequestId request_id,
+                             Address from_address) {
+    Log("redirecting client to known Leader with port ", follower.leader_address.last_known_port);
+
+    const WriteResponse<WriteResponseValue> res{
+        .success = false,
+        .retry_leader = follower.leader_address,
+    };
+
+    io_.Send(from_address, request_id, res);
+
+    return std::nullopt;
+  }
+
+  std::optional<Role> Handle(Candidate & /* variable */, WriteRequest<WriteOperation> && /* variable */,
+                             RequestId request_id, Address from_address) {
+    Log("received WriteRequest - not redirecting because no Leader is known");
+
+    const WriteResponse<WriteResponseValue> res{
+        .success = false,
+    };
+
+    io_.Send(from_address, request_id, res);
+
+    Cron();
+
+    return std::nullopt;
+  }
+
+  // only leaders actually handle replication requests from clients
+  std::optional<Role> Handle(Leader &leader, WriteRequest<WriteOperation> &&req, RequestId request_id,
+                             Address from_address) {
+    Log("handling WriteRequest");
+
+    // we are the leader. add item to log and send Append to peers
+    MG_ASSERT(state_.term >= LastLogTerm());
+    state_.log.emplace_back(std::pair(state_.term, std::move(req.operation)));
+
+    LogIndex log_index = state_.log.size() - 1;
+
+    PendingClientRequest pcr{
+        .request_id = request_id,
+        .address = from_address,
+        .received_at = io_.Now(),
+    };
+
+    leader.pending_client_requests.emplace(log_index, pcr);
+
+    if (peers_.empty()) {
+      BumpCommitIndexAndReplyToClients(leader);
+    } else {
+      BroadcastAppendEntries(leader.followers);
+    }
+
+    return std::nullopt;
+  }
+};
+
+};  // namespace memgraph::io::rsm

src/io/rsm/rsm_client.hpp

@@ -0,0 +1,136 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <iostream>
+#include <optional>
+#include <vector>
+
+#include "io/address.hpp"
+#include "io/rsm/raft.hpp"
+#include "utils/result.hpp"
+
+namespace memgraph::io::rsm {
+
+using memgraph::io::Address;
+using memgraph::io::Duration;
+using memgraph::io::ResponseEnvelope;
+using memgraph::io::ResponseFuture;
+using memgraph::io::ResponseResult;
+using memgraph::io::Time;
+using memgraph::io::TimedOut;
+using memgraph::io::rsm::ReadRequest;
+using memgraph::io::rsm::ReadResponse;
+using memgraph::io::rsm::WriteRequest;
+using memgraph::io::rsm::WriteResponse;
+using memgraph::utils::BasicResult;
+
+template <typename IoImpl, typename WriteRequestT, typename WriteResponseT, typename ReadRequestT,
+          typename ReadResponseT>
+class RsmClient {
+  using ServerPool = std::vector<Address>;
+
+  Io<IoImpl> io_;
+  Address leader_;
+  ServerPool server_addrs_;
+
+  template <typename ResponseT>
+  void PossiblyRedirectLeader(const ResponseT &response) {
+    if (response.retry_leader) {
+      MG_ASSERT(!response.success, "retry_leader should never be set for successful responses");
+      leader_ = response.retry_leader.value();
+      spdlog::debug("client redirected to leader server {}", leader_.ToString());
+    } else if (!response.success) {
+      std::uniform_int_distribution<size_t> addr_distrib(0, (server_addrs_.size() - 1));
+      size_t addr_index = io_.Rand(addr_distrib);
+      leader_ = server_addrs_[addr_index];
+
+      spdlog::debug(
+          "client NOT redirected to leader server despite our success failing to be processed (it probably was sent to "
+          "a RSM Candidate) trying a random one at index {} with address {}",
+          addr_index, leader_.ToString());
+    }
+  }
+
+ public:
+  RsmClient(Io<IoImpl> io, Address leader, ServerPool server_addrs)
+      : io_{io}, leader_{leader}, server_addrs_{server_addrs} {}
+
+  RsmClient() = delete;
+
+  BasicResult<TimedOut, WriteResponseT> SendWriteRequest(WriteRequestT req) {
+    WriteRequest<WriteRequestT> client_req;
+    client_req.operation = req;
+
+    const Duration overall_timeout = io_.GetDefaultTimeout();
+    const Time before = io_.Now();
+
+    do {
+      spdlog::debug("client sending WriteRequest to Leader {}", leader_.ToString());
+      ResponseFuture<WriteResponse<WriteResponseT>> response_future =
+          io_.template Request<WriteRequest<WriteRequestT>, WriteResponse<WriteResponseT>>(leader_, client_req);
+      ResponseResult<WriteResponse<WriteResponseT>> response_result = std::move(response_future).Wait();
+
+      if (response_result.HasError()) {
+        spdlog::debug("client timed out while trying to communicate with leader server {}", leader_.ToString());
+        return response_result.GetError();
+      }
+
+      ResponseEnvelope<WriteResponse<WriteResponseT>> &&response_envelope = std::move(response_result.GetValue());
+      WriteResponse<WriteResponseT> &&write_response = std::move(response_envelope.message);
+
+      if (write_response.success) {
+        return std::move(write_response.write_return);
+      }
+
+      PossiblyRedirectLeader(write_response);
+    } while (io_.Now() < before + overall_timeout);
+
+    return TimedOut{};
+  }
+
+  BasicResult<TimedOut, ReadResponseT> SendReadRequest(ReadRequestT req) {
+    ReadRequest<ReadRequestT> read_req;
+    read_req.operation = req;
+
+    const Duration overall_timeout = io_.GetDefaultTimeout();
+    const Time before = io_.Now();
+
+    do {
+      spdlog::debug("client sending ReadRequest to Leader {}", leader_.ToString());
+
+      ResponseFuture<ReadResponse<ReadResponseT>> get_response_future =
+          io_.template Request<ReadRequest<ReadRequestT>, ReadResponse<ReadResponseT>>(leader_, read_req);
+
+      // receive response
+      ResponseResult<ReadResponse<ReadResponseT>> get_response_result = std::move(get_response_future).Wait();
+
+      if (get_response_result.HasError()) {
+        spdlog::debug("client timed out while trying to communicate with leader server {}", leader_.ToString());
+        return get_response_result.GetError();
+      }
+
+      ResponseEnvelope<ReadResponse<ReadResponseT>> &&get_response_envelope = std::move(get_response_result.GetValue());
+      ReadResponse<ReadResponseT> &&read_get_response = std::move(get_response_envelope.message);
+
+      if (read_get_response.success) {
+        return std::move(read_get_response.read_return);
+      }
+
+      PossiblyRedirectLeader(read_get_response);
+    } while (io_.Now() < before + overall_timeout);
+
+    return TimedOut{};
+  }
+};
+
+}  // namespace memgraph::io::rsm

src/io/rsm/shard_rsm.hpp

@@ -0,0 +1,155 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+/// The ShardRsm is a simple in-memory raft-backed kv store that can be used for simple testing
+/// and implementation of some query engine logic before storage engines are fully implemented.
+///
+/// To implement multiple read and write commands, change the StorageRead* and StorageWrite* requests
+/// and responses to a std::variant of the different options, and route them to specific handlers in
+/// the ShardRsm's Read and Apply methods. Remember that Read is called immediately when the Raft
+/// leader receives the request, and does not replicate anything over Raft. Apply is called only
+/// AFTER the StorageWriteRequest is replicated to a majority of Raft peers, and the result of calling
+/// ShardRsm::Apply(StorageWriteRequest) is returned to the client that submitted the request.
+
+#include <deque>
+#include <iostream>
+#include <map>
+#include <optional>
+#include <set>
+#include <thread>
+#include <vector>
+
+#include "coordinator/hybrid_logical_clock.hpp"
+#include "io/address.hpp"
+#include "io/rsm/raft.hpp"
+#include "storage/v3/id_types.hpp"
+#include "storage/v3/property_value.hpp"
+#include "utils/logging.hpp"
+
+namespace memgraph::io::rsm {
+
+using memgraph::coordinator::Hlc;
+using memgraph::storage::v3::LabelId;
+using memgraph::storage::v3::PropertyValue;
+
+using ShardRsmKey = std::vector<PropertyValue>;
+
+struct StorageWriteRequest {
+  LabelId label_id;
+  Hlc transaction_id;
+  ShardRsmKey key;
+  std::optional<int> value;
+};
+
+struct StorageWriteResponse {
+  bool shard_rsm_success;
+  std::optional<int> last_value;
+  // Only has a value if the given shard does not contain the requested key
+  std::optional<Hlc> latest_known_shard_map_version{std::nullopt};
+};
+
+struct StorageReadRequest {
+  LabelId label_id;
+  Hlc transaction_id;
+  ShardRsmKey key;
+};
+
+struct StorageReadResponse {
+  bool shard_rsm_success;
+  std::optional<int> value;
+  // Only has a value if the given shard does not contain the requested key
+  std::optional<Hlc> latest_known_shard_map_version{std::nullopt};
+};
+
+class ShardRsm {
+  std::map<ShardRsmKey, int> state_;
+  ShardRsmKey minimum_key_;
+  std::optional<ShardRsmKey> maximum_key_{std::nullopt};
+  Hlc shard_map_version_;
+
+  // The key is not located in this shard
+  bool IsKeyInRange(const ShardRsmKey &key) const {
+    if (maximum_key_) [[likely]] {
+      return (key >= minimum_key_ && key <= maximum_key_);
+    }
+    return key >= minimum_key_;
+  }
+
+ public:
+  StorageReadResponse Read(StorageReadRequest request) const {
+    StorageReadResponse ret;
+
+    if (!IsKeyInRange(request.key)) {
+      ret.latest_known_shard_map_version = shard_map_version_;
+      ret.shard_rsm_success = false;
+    } else if (state_.contains(request.key)) {
+      ret.value = state_.at(request.key);
+      ret.shard_rsm_success = true;
+    } else {
+      ret.shard_rsm_success = false;
+      ret.value = std::nullopt;
+    }
+    return ret;
+  }
+
+  StorageWriteResponse Apply(StorageWriteRequest request) {
+    StorageWriteResponse ret;
+
+    // Key is outside the prohibited range
+    if (!IsKeyInRange(request.key)) {
+      ret.latest_known_shard_map_version = shard_map_version_;
+      ret.shard_rsm_success = false;
+    }
+    // Key exist
+    else if (state_.contains(request.key)) {
+      auto &val = state_[request.key];
+
+      /*
+       *   Delete
+       */
+      if (!request.value) {
+        ret.shard_rsm_success = true;
+        ret.last_value = val;
+        state_.erase(state_.find(request.key));
+      }
+
+      /*
+       *   Update
+       */
+      // Does old_value match?
+      if (request.value == val) {
+        ret.last_value = val;
+        ret.shard_rsm_success = true;
+
+        val = request.value.value();
+
+      } else {
+        ret.last_value = val;
+        ret.shard_rsm_success = false;
+      }
+    }
+    /*
+     *   Create
+     */
+    else {
+      ret.last_value = std::nullopt;
+      ret.shard_rsm_success = true;
+
+      state_.emplace(request.key, request.value.value());
+    }
+
+    return ret;
+  }
+};
+
+}  // namespace memgraph::io::rsm

src/io/simulator/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(io_simulator_sources
+    simulator_handle.cpp)
+
+find_package(fmt REQUIRED)
+find_package(Threads REQUIRED)
+
+add_library(mg-io-simulator STATIC ${io_simulator_sources})
+target_link_libraries(mg-io-simulator stdc++fs Threads::Threads fmt::fmt mg-utils)

src/io/simulator/simulator.hpp

@@ -0,0 +1,51 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <memory>
+#include <random>
+
+#include "io/address.hpp"
+#include "io/simulator/simulator_config.hpp"
+#include "io/simulator/simulator_handle.hpp"
+#include "io/simulator/simulator_transport.hpp"
+
+namespace memgraph::io::simulator {
+class Simulator {
+  std::mt19937 rng_;
+  std::shared_ptr<SimulatorHandle> simulator_handle_;
+  uint16_t auto_port_ = 0;
+
+ public:
+  explicit Simulator(SimulatorConfig config)
+      : rng_(std::mt19937{config.rng_seed}), simulator_handle_{std::make_shared<SimulatorHandle>(config)} {}
+
+  void ShutDown() { simulator_handle_->ShutDown(); }
+
+  Io<SimulatorTransport> RegisterNew() {
+    Address address = Address::TestAddress(auto_port_++);
+    return Register(address);
+  }
+
+  Io<SimulatorTransport> Register(Address address) {
+    std::uniform_int_distribution<uint64_t> seed_distrib;
+    uint64_t seed = seed_distrib(rng_);
+    return Io{SimulatorTransport{simulator_handle_, address, seed}, address};
+  }
+
+  void IncrementServerCountAndWaitForQuiescentState(Address address) {
+    simulator_handle_->IncrementServerCountAndWaitForQuiescentState(address);
+  }
+
+  SimulatorStats Stats() { return simulator_handle_->Stats(); }
+};
+};  // namespace memgraph::io::simulator

src/io/simulator/simulator_config.hpp

@@ -0,0 +1,30 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <chrono>
+
+#include "io/time.hpp"
+
+namespace memgraph::io::simulator {
+
+using memgraph::io::Time;
+
+struct SimulatorConfig {
+  uint8_t drop_percent = 0;
+  bool perform_timeouts = false;
+  bool scramble_messages = true;
+  uint64_t rng_seed = 0;
+  Time start_time = Time::min();
+  Time abort_time = Time::max();
+};
+};  // namespace memgraph::io::simulator

src/io/simulator/simulator_handle.cpp

@@ -0,0 +1,142 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "io/simulator/simulator_handle.hpp"
+#include "io/address.hpp"
+#include "io/errors.hpp"
+#include "io/simulator/simulator_config.hpp"
+#include "io/simulator/simulator_stats.hpp"
+#include "io/time.hpp"
+#include "io/transport.hpp"
+
+namespace memgraph::io::simulator {
+
+using memgraph::io::Duration;
+using memgraph::io::Time;
+
+void SimulatorHandle::ShutDown() {
+  std::unique_lock<std::mutex> lock(mu_);
+  should_shut_down_ = true;
+  cv_.notify_all();
+}
+
+bool SimulatorHandle::ShouldShutDown() const {
+  std::unique_lock<std::mutex> lock(mu_);
+  return should_shut_down_;
+}
+
+void SimulatorHandle::IncrementServerCountAndWaitForQuiescentState(Address address) {
+  std::unique_lock<std::mutex> lock(mu_);
+  server_addresses_.insert(address);
+
+  while (true) {
+    const size_t blocked_servers = blocked_on_receive_.size();
+
+    const bool all_servers_blocked = blocked_servers == server_addresses_.size();
+
+    if (all_servers_blocked) {
+      return;
+    }
+
+    cv_.wait(lock);
+  }
+}
+
+bool SimulatorHandle::MaybeTickSimulator() {
+  std::unique_lock<std::mutex> lock(mu_);
+
+  const size_t blocked_servers = blocked_on_receive_.size();
+
+  if (blocked_servers < server_addresses_.size()) {
+    // we only need to advance the simulator when all
+    // servers have reached a quiescent state, blocked
+    // on their own futures or receive methods.
+    return false;
+  }
+
+  stats_.simulator_ticks++;
+
+  cv_.notify_all();
+
+  TimeoutPromisesPastDeadline();
+
+  if (in_flight_.empty()) {
+    // return early here because there are no messages to schedule
+
+    // We tick the clock forward when all servers are blocked but
+    // there are no in-flight messages to schedule delivery of.
+    std::poisson_distribution<> time_distrib(50);
+    Duration clock_advance = std::chrono::microseconds{time_distrib(rng_)};
+    cluster_wide_time_microseconds_ += clock_advance;
+
+    MG_ASSERT(cluster_wide_time_microseconds_ < config_.abort_time,
+              "Cluster has executed beyond its configured abort_time, and something may be failing to make progress "
+              "in an expected amount of time.");
+    return true;
+  }
+
+  if (config_.scramble_messages) {
+    // scramble messages
+    std::uniform_int_distribution<size_t> swap_distrib(0, in_flight_.size() - 1);
+    const size_t swap_index = swap_distrib(rng_);
+    std::swap(in_flight_[swap_index], in_flight_.back());
+  }
+
+  auto [to_address, opaque_message] = std::move(in_flight_.back());
+  in_flight_.pop_back();
+
+  std::uniform_int_distribution<int> drop_distrib(0, 99);
+  const int drop_threshold = drop_distrib(rng_);
+  const bool should_drop = drop_threshold < config_.drop_percent;
+
+  if (should_drop) {
+    stats_.dropped_messages++;
+  }
+
+  PromiseKey promise_key{.requester_address = to_address,
+                         .request_id = opaque_message.request_id,
+                         .replier_address = opaque_message.from_address};
+
+  if (promises_.contains(promise_key)) {
+    // complete waiting promise if it's there
+    DeadlineAndOpaquePromise dop = std::move(promises_.at(promise_key));
+    promises_.erase(promise_key);
+
+    const bool normal_timeout = config_.perform_timeouts && (dop.deadline < cluster_wide_time_microseconds_);
+
+    if (should_drop || normal_timeout) {
+      stats_.timed_out_requests++;
+      dop.promise.TimeOut();
+    } else {
+      stats_.total_responses++;
+      dop.promise.Fill(std::move(opaque_message));
+    }
+  } else if (should_drop) {
+    // don't add it anywhere, let it drop
+  } else {
+    // add to can_receive_ if not
+    const auto &[om_vec, inserted] = can_receive_.try_emplace(to_address, std::vector<OpaqueMessage>());
+    om_vec->second.emplace_back(std::move(opaque_message));
+  }
+
+  return true;
+}
+
+Time SimulatorHandle::Now() const {
+  std::unique_lock<std::mutex> lock(mu_);
+  return cluster_wide_time_microseconds_;
+}
+
+SimulatorStats SimulatorHandle::Stats() {
+  std::unique_lock<std::mutex> lock(mu_);
+  return stats_;
+}
+}  // namespace memgraph::io::simulator

src/io/simulator/simulator_handle.hpp

@@ -0,0 +1,177 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <any>
+#include <compare>
+#include <iostream>
+#include <map>
+#include <memory>
+#include <optional>
+#include <set>
+#include <utility>
+#include <variant>
+#include <vector>
+
+#include "io/address.hpp"
+#include "io/errors.hpp"
+#include "io/message_conversion.hpp"
+#include "io/simulator/simulator_config.hpp"
+#include "io/simulator/simulator_stats.hpp"
+#include "io/time.hpp"
+#include "io/transport.hpp"
+
+namespace memgraph::io::simulator {
+
+class SimulatorHandle {
+  mutable std::mutex mu_{};
+  mutable std::condition_variable cv_;
+
+  // messages that have not yet been scheduled or dropped
+  std::vector<std::pair<Address, OpaqueMessage>> in_flight_;
+
+  // the responses to requests that are being waited on
+  std::map<PromiseKey, DeadlineAndOpaquePromise> promises_;
+
+  // messages that are sent to servers that may later receive them
+  std::map<Address, std::vector<OpaqueMessage>> can_receive_;
+
+  Time cluster_wide_time_microseconds_;
+  bool should_shut_down_ = false;
+  SimulatorStats stats_;
+  std::set<Address> blocked_on_receive_;
+  std::set<Address> server_addresses_;
+  std::mt19937 rng_;
+  SimulatorConfig config_;
+
+  void TimeoutPromisesPastDeadline() {
+    const Time now = cluster_wide_time_microseconds_;
+    for (auto it = promises_.begin(); it != promises_.end();) {
+      auto &[promise_key, dop] = *it;
+      if (dop.deadline < now) {
+        spdlog::info("timing out request from requester {} to replier {}.", promise_key.requester_address.ToString(),
+                     promise_key.replier_address.ToString());
+        std::move(dop).promise.TimeOut();
+        it = promises_.erase(it);
+
+        stats_.timed_out_requests++;
+      } else {
+        ++it;
+      }
+    }
+  }
+
+ public:
+  explicit SimulatorHandle(SimulatorConfig config)
+      : cluster_wide_time_microseconds_(config.start_time), rng_(config.rng_seed), config_(config) {}
+
+  void IncrementServerCountAndWaitForQuiescentState(Address address);
+
+  /// This method causes most of the interesting simulation logic to happen, wrt network behavior.
+  /// It checks to see if all background "server" threads are blocked on new messages, and if so,
+  /// it will decide whether to drop, reorder, or deliver in-flight messages based on the SimulatorConfig
+  /// that was used to create the Simulator.
+  bool MaybeTickSimulator();
+
+  void ShutDown();
+
+  bool ShouldShutDown() const;
+
+  template <Message Request, Message Response>
+  void SubmitRequest(Address to_address, Address from_address, RequestId request_id, Request &&request,
+                     Duration timeout, ResponsePromise<Response> &&promise) {
+    std::unique_lock<std::mutex> lock(mu_);
+
+    const Time deadline = cluster_wide_time_microseconds_ + timeout;
+
+    std::any message(request);
+    OpaqueMessage om{.to_address = to_address,
+                     .from_address = from_address,
+                     .request_id = request_id,
+                     .message = std::move(message)};
+    in_flight_.emplace_back(std::make_pair(to_address, std::move(om)));
+
+    PromiseKey promise_key{.requester_address = from_address, .request_id = request_id, .replier_address = to_address};
+    OpaquePromise opaque_promise(std::move(promise).ToUnique());
+    DeadlineAndOpaquePromise dop{.deadline = deadline, .promise = std::move(opaque_promise)};
+    promises_.emplace(std::move(promise_key), std::move(dop));
+
+    stats_.total_messages++;
+    stats_.total_requests++;
+
+    cv_.notify_all();
+  }
+
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) RequestResult<Ms...> Receive(const Address &receiver, Duration timeout) {
+    std::unique_lock<std::mutex> lock(mu_);
+
+    blocked_on_receive_.emplace(receiver);
+
+    const Time deadline = cluster_wide_time_microseconds_ + timeout;
+
+    while (!should_shut_down_ && (cluster_wide_time_microseconds_ < deadline)) {
+      if (can_receive_.contains(receiver)) {
+        std::vector<OpaqueMessage> &can_rx = can_receive_.at(receiver);
+        if (!can_rx.empty()) {
+          OpaqueMessage message = std::move(can_rx.back());
+          can_rx.pop_back();
+
+          // TODO(tyler) search for item in can_receive_ that matches the desired types, rather
+          // than asserting that the last item in can_rx matches.
+          auto m_opt = std::move(message).Take<Ms...>();
+
+          blocked_on_receive_.erase(receiver);
+
+          return std::move(m_opt).value();
+        }
+      }
+
+      lock.unlock();
+      bool made_progress = MaybeTickSimulator();
+      lock.lock();
+      if (!should_shut_down_ && !made_progress) {
+        cv_.wait(lock);
+      }
+    }
+
+    blocked_on_receive_.erase(receiver);
+
+    return TimedOut{};
+  }
+
+  template <Message M>
+  void Send(Address to_address, Address from_address, RequestId request_id, M message) {
+    std::unique_lock<std::mutex> lock(mu_);
+    std::any message_any(std::move(message));
+    OpaqueMessage om{.to_address = to_address,
+                     .from_address = from_address,
+                     .request_id = request_id,
+                     .message = std::move(message_any)};
+    in_flight_.emplace_back(std::make_pair(std::move(to_address), std::move(om)));
+
+    stats_.total_messages++;
+
+    cv_.notify_all();
+  }
+
+  Time Now() const;
+
+  template <class D = std::poisson_distribution<>, class Return = uint64_t>
+  Return Rand(D distrib) {
+    std::unique_lock<std::mutex> lock(mu_);
+    return distrib(rng_);
+  }
+
+  SimulatorStats Stats();
+};
+};  // namespace memgraph::io::simulator

src/io/simulator/simulator_stats.hpp

@@ -0,0 +1,25 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <cstdint>
+
+namespace memgraph::io::simulator {
+struct SimulatorStats {
+  uint64_t total_messages = 0;
+  uint64_t dropped_messages = 0;
+  uint64_t timed_out_requests = 0;
+  uint64_t total_requests = 0;
+  uint64_t total_responses = 0;
+  uint64_t simulator_ticks = 0;
+};
+};  // namespace memgraph::io::simulator

src/io/simulator/simulator_transport.hpp

@@ -0,0 +1,67 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <memory>
+#include <utility>
+
+#include "io/address.hpp"
+#include "io/simulator/simulator_handle.hpp"
+#include "io/time.hpp"
+
+namespace memgraph::io::simulator {
+
+using memgraph::io::Duration;
+using memgraph::io::Time;
+
+class SimulatorTransport {
+  std::shared_ptr<SimulatorHandle> simulator_handle_;
+  const Address address_;
+  std::mt19937 rng_;
+
+ public:
+  SimulatorTransport(std::shared_ptr<SimulatorHandle> simulator_handle, Address address, uint64_t seed)
+      : simulator_handle_(simulator_handle), address_(address), rng_(std::mt19937{seed}) {}
+
+  template <Message RequestT, Message ResponseT>
+  ResponseFuture<ResponseT> Request(Address to_address, Address from_address, uint64_t request_id, RequestT request,
+                                    Duration timeout) {
+    std::function<bool()> maybe_tick_simulator = [this] { return simulator_handle_->MaybeTickSimulator(); };
+    auto [future, promise] =
+        memgraph::io::FuturePromisePairWithNotifier<ResponseResult<ResponseT>>(maybe_tick_simulator);
+
+    simulator_handle_->SubmitRequest(to_address, from_address, request_id, std::move(request), timeout,
+                                     std::move(promise));
+
+    return std::move(future);
+  }
+
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) RequestResult<Ms...> Receive(Address receiver_address, Duration timeout) {
+    return simulator_handle_->template Receive<Ms...>(receiver_address, timeout);
+  }
+
+  template <Message M>
+  void Send(Address to_address, Address from_address, uint64_t request_id, M message) {
+    return simulator_handle_->template Send<M>(to_address, from_address, request_id, message);
+  }
+
+  Time Now() const { return simulator_handle_->Now(); }
+
+  bool ShouldShutDown() const { return simulator_handle_->ShouldShutDown(); }
+
+  template <class D = std::poisson_distribution<>, class Return = uint64_t>
+  Return Rand(D distrib) {
+    return distrib(rng_);
+  }
+};
+};  // namespace memgraph::io::simulator

src/io/time.hpp

@@ -10,10 +10,12 @@
 // licenses/APL.txt.
 
 #pragma once
-#include <cstdint>
 
-namespace memgraph::storage::v3::replication {
-enum class ReplicationMode : std::uint8_t { SYNC, ASYNC };
+#include <chrono>
 
-enum class ReplicaState : std::uint8_t { READY, REPLICATING, RECOVERY, INVALID };
-}  // namespace memgraph::storage::v3::replication
+namespace memgraph::io {
+
+using Duration = std::chrono::microseconds;
+using Time = std::chrono::time_point<std::chrono::system_clock, Duration>;
+
+}  // namespace memgraph::io

src/io/transport.hpp

@@ -0,0 +1,144 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <chrono>
+#include <concepts>
+#include <random>
+#include <variant>
+
+#include "io/address.hpp"
+#include "io/errors.hpp"
+#include "io/future.hpp"
+#include "io/time.hpp"
+#include "utils/result.hpp"
+
+namespace memgraph::io {
+
+using memgraph::utils::BasicResult;
+
+// TODO(tyler) ensure that Message continues to represent
+// reasonable constraints around message types over time,
+// as we adapt things to use Thrift-generated message types.
+template <typename T>
+concept Message = std::same_as<T, std::decay_t<T>>;
+
+using RequestId = uint64_t;
+
+template <Message M>
+struct ResponseEnvelope {
+  M message;
+  RequestId request_id;
+  Address to_address;
+  Address from_address;
+};
+
+template <Message M>
+using ResponseResult = BasicResult<TimedOut, ResponseEnvelope<M>>;
+
+template <Message M>
+using ResponseFuture = memgraph::io::Future<ResponseResult<M>>;
+
+template <Message M>
+using ResponsePromise = memgraph::io::Promise<ResponseResult<M>>;
+
+template <Message... Ms>
+struct RequestEnvelope {
+  std::variant<Ms...> message;
+  RequestId request_id;
+  Address to_address;
+  Address from_address;
+};
+
+template <Message... Ms>
+using RequestResult = BasicResult<TimedOut, RequestEnvelope<Ms...>>;
+
+template <typename I>
+class Io {
+  I implementation_;
+  Address address_;
+  RequestId request_id_counter_ = 0;
+  Duration default_timeout_ = std::chrono::microseconds{100000};
+
+ public:
+  Io(I io, Address address) : implementation_(io), address_(address) {}
+
+  /// Set the default timeout for all requests that are issued
+  /// without an explicit timeout set.
+  void SetDefaultTimeout(Duration timeout) { default_timeout_ = timeout; }
+
+  /// Returns the current default timeout for this Io instance.
+  Duration GetDefaultTimeout() { return default_timeout_; }
+
+  /// Issue a request with an explicit timeout in microseconds provided. This tends to be used by clients.
+  template <Message RequestT, Message ResponseT>
+  ResponseFuture<ResponseT> RequestWithTimeout(Address address, RequestT request, Duration timeout) {
+    const RequestId request_id = ++request_id_counter_;
+    const Address from_address = address_;
+    return implementation_.template Request<RequestT, ResponseT>(address, from_address, request_id, request, timeout);
+  }
+
+  /// Issue a request that times out after the default timeout. This tends
+  /// to be used by clients.
+  template <Message RequestT, Message ResponseT>
+  ResponseFuture<ResponseT> Request(Address to_address, RequestT request) {
+    const RequestId request_id = ++request_id_counter_;
+    const Duration timeout = default_timeout_;
+    const Address from_address = address_;
+    return implementation_.template Request<RequestT, ResponseT>(to_address, from_address, request_id,
+                                                                 std::move(request), timeout);
+  }
+
+  /// Wait for an explicit number of microseconds for a request of one of the
+  /// provided types to arrive. This tends to be used by servers.
+  template <Message... Ms>
+  RequestResult<Ms...> ReceiveWithTimeout(Duration timeout) {
+    return implementation_.template Receive<Ms...>(address_, timeout);
+  }
+
+  /// Wait the default number of microseconds for a request of one of the
+  /// provided types to arrive. This tends to be used by servers.
+  template <Message... Ms>
+  requires(sizeof...(Ms) > 0) RequestResult<Ms...> Receive() {
+    const Duration timeout = default_timeout_;
+    return implementation_.template Receive<Ms...>(address_, timeout);
+  }
+
+  /// Send a message in a best-effort fashion. This is used for messaging where
+  /// responses are not necessarily expected, and for servers to respond to requests.
+  /// If you need reliable delivery, this must be built on-top. TCP is not enough for most use cases.
+  template <Message M>
+  void Send(Address to_address, RequestId request_id, M message) {
+    Address from_address = address_;
+    return implementation_.template Send<M>(to_address, from_address, request_id, std::move(message));
+  }
+
+  /// The current system time. This time source should be preferred over any other,
+  /// because it lets us deterministically control clocks from tests for making
+  /// things like timeouts deterministic.
+  Time Now() const { return implementation_.Now(); }
+
+  /// Returns true if the system should shut-down.
+  bool ShouldShutDown() const { return implementation_.ShouldShutDown(); }
+
+  /// Returns a random number within the specified distribution.
+  template <class D = std::poisson_distribution<>, class Return = uint64_t>
+  Return Rand(D distrib) {
+    return implementation_.template Rand<D, Return>(distrib);
+  }
+
+  Address GetAddress() { return address_; }
+  void SetAddress(Address address) { address_ = address; }
+
+  Io<I> ForkLocal() { return Io(implementation_, address_.ForkUniqueAddress()); }
+};
+};  // namespace memgraph::io

src/machine_manager/machine_config.hpp

@@ -0,0 +1,42 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <boost/asio/ip/tcp.hpp>
+#include "io/address.hpp"
+#include "storage/v3/property_value.hpp"
+#include "storage/v3/schemas.hpp"
+
+namespace memgraph::machine_manager {
+
+using memgraph::io::Address;
+using memgraph::storage::v3::SchemaProperty;
+using CompoundKey = std::vector<memgraph::storage::v3::PropertyValue>;
+
+struct InitialLabelSpace {
+  std::string label_name;
+  std::vector<SchemaProperty> schema;
+  size_t replication_factor;
+  std::vector<CompoundKey> split_points;
+};
+
+struct MachineConfig {
+  std::vector<InitialLabelSpace> initial_label_spaces;
+  std::vector<Address> coordinator_addresses;
+  bool is_storage;
+  bool is_coordinator;
+  bool is_query_engine;
+  boost::asio::ip::address listen_ip;
+  uint16_t listen_port;
+};
+
+}  // namespace memgraph::machine_manager

src/machine_manager/machine_manager.hpp

@@ -0,0 +1,177 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <coordinator/coordinator_rsm.hpp>
+#include <io/message_conversion.hpp>
+#include <io/messages.hpp>
+#include <io/rsm/rsm_client.hpp>
+#include <io/time.hpp>
+#include <machine_manager/machine_config.hpp>
+#include <storage/v3/shard_manager.hpp>
+
+namespace memgraph::machine_manager {
+
+using memgraph::coordinator::Coordinator;
+using memgraph::coordinator::CoordinatorReadRequests;
+using memgraph::coordinator::CoordinatorReadResponses;
+using memgraph::coordinator::CoordinatorRsm;
+using memgraph::coordinator::CoordinatorWriteRequests;
+using memgraph::coordinator::CoordinatorWriteResponses;
+using memgraph::io::ConvertVariant;
+using memgraph::io::Duration;
+using memgraph::io::RequestId;
+using memgraph::io::Time;
+using memgraph::io::messages::CoordinatorMessages;
+using memgraph::io::messages::ShardManagerMessages;
+using memgraph::io::messages::ShardMessages;
+using memgraph::io::messages::StorageReadRequest;
+using memgraph::io::messages::StorageWriteRequest;
+using memgraph::io::rsm::AppendRequest;
+using memgraph::io::rsm::AppendResponse;
+using memgraph::io::rsm::ReadRequest;
+using memgraph::io::rsm::VoteRequest;
+using memgraph::io::rsm::VoteResponse;
+using memgraph::io::rsm::WriteRequest;
+using memgraph::io::rsm::WriteResponse;
+using memgraph::storage::v3::ShardManager;
+
+/// The MachineManager is responsible for:
+/// * starting the entire system and ensuring that high-level
+///   operational requirements continue to be met
+/// * acting as a machine's single caller of Io::Receive
+/// * routing incoming messages from the Io interface to the
+///   appropriate Coordinator or to the StorageManager
+///   (it's not necessary to route anything in this layer
+///   to the query engine because the query engine only
+///   communicates using higher-level Futures that will
+///   be filled immediately when the response comes in
+///   at the lower-level transport layer.
+///
+/// Every storage engine has exactly one RsmEngine.
+template <typename IoImpl>
+class MachineManager {
+  io::Io<IoImpl> io_;
+  MachineConfig config_;
+  CoordinatorRsm<IoImpl> coordinator_;
+  ShardManager<IoImpl> shard_manager_;
+  Time next_cron_;
+
+ public:
+  // TODO initialize ShardManager with "real" coordinator addresses instead of io.GetAddress
+  // which is only true for single-machine config.
+  MachineManager(io::Io<IoImpl> io, MachineConfig config, Coordinator coordinator)
+      : io_(io),
+        config_(config),
+        coordinator_{std::move(io.ForkLocal()), {}, std::move(coordinator)},
+        shard_manager_(ShardManager{io.ForkLocal(), coordinator_.GetAddress()}) {}
+
+  Address CoordinatorAddress() { return coordinator_.GetAddress(); }
+
+  void Run() {
+    while (!io_.ShouldShutDown()) {
+      const auto now = io_.Now();
+
+      if (now >= next_cron_) {
+        next_cron_ = Cron();
+      }
+
+      Duration receive_timeout = next_cron_ - now;
+
+      // Note: this parameter pack must be kept in-sync with the ReceiveWithTimeout parameter pack below
+      using AllMessages =
+          std::variant<ReadRequest<CoordinatorReadRequests>, AppendRequest<CoordinatorWriteRequests>, AppendResponse,
+                       WriteRequest<CoordinatorWriteRequests>, VoteRequest, VoteResponse,
+                       WriteResponse<CoordinatorWriteResponses>, ReadRequest<StorageReadRequest>,
+                       AppendRequest<StorageWriteRequest>, WriteRequest<StorageWriteRequest>>;
+
+      spdlog::info("MM waiting on Receive");
+
+      // Note: this parameter pack must be kept in-sync with the AllMessages parameter pack above
+      auto request_result = io_.template ReceiveWithTimeout<
+          ReadRequest<CoordinatorReadRequests>, AppendRequest<CoordinatorWriteRequests>, AppendResponse,
+          WriteRequest<CoordinatorWriteRequests>, VoteRequest, VoteResponse, WriteResponse<CoordinatorWriteResponses>,
+          ReadRequest<StorageReadRequest>, AppendRequest<StorageWriteRequest>, WriteRequest<StorageWriteRequest>>(
+          receive_timeout);
+
+      if (request_result.HasError()) {
+        // time to do Cron
+        spdlog::info("MM got timeout");
+        continue;
+      }
+
+      auto &&request_envelope = std::move(request_result.GetValue());
+
+      spdlog::info("MM got message to {}", request_envelope.to_address.ToString());
+
+      // If message is for the coordinator, cast it to subset and pass it to the coordinator
+      bool to_coordinator = coordinator_.GetAddress() == request_envelope.to_address;
+      spdlog::info("coordinator: {}", coordinator_.GetAddress().ToString());
+      if (to_coordinator) {
+        std::optional<CoordinatorMessages> conversion_attempt =
+            ConvertVariant<AllMessages, ReadRequest<CoordinatorReadRequests>, AppendRequest<CoordinatorWriteRequests>,
+                           AppendResponse, WriteRequest<CoordinatorWriteRequests>, VoteRequest, VoteResponse>(
+                std::move(request_envelope.message));
+
+        MG_ASSERT(conversion_attempt.has_value(), "coordinator message conversion failed");
+
+        spdlog::info("got coordinator message");
+
+        CoordinatorMessages &&cm = std::move(conversion_attempt.value());
+
+        coordinator_.Handle(std::forward<CoordinatorMessages>(cm), request_envelope.request_id,
+                            request_envelope.from_address);
+        continue;
+      }
+
+      bool to_sm = shard_manager_.GetAddress() == request_envelope.to_address;
+      spdlog::info("smm: {}", shard_manager_.GetAddress().ToString());
+      if (to_sm) {
+        std::optional<ShardManagerMessages> conversion_attempt =
+            ConvertVariant<AllMessages, WriteResponse<CoordinatorWriteResponses>>(std::move(request_envelope.message));
+
+        MG_ASSERT(conversion_attempt.has_value(), "shard manager message conversion failed");
+
+        spdlog::info("got shard manager message");
+
+        ShardManagerMessages &&smm = std::move(conversion_attempt.value());
+        shard_manager_.Receive(std::forward<ShardManagerMessages>(smm), request_envelope.request_id,
+                               request_envelope.from_address);
+        continue;
+      }
+
+      // treat this as a message to a specific shard rsm and cast it accordingly
+
+      std::optional<ShardMessages> conversion_attempt =
+          ConvertVariant<AllMessages, ReadRequest<StorageReadRequest>, AppendRequest<StorageWriteRequest>,
+                         AppendResponse, WriteRequest<StorageWriteRequest>, VoteRequest, VoteResponse>(
+              std::move(request_envelope.message));
+
+      MG_ASSERT(conversion_attempt.has_value(), "shard rsm message conversion failed for {}",
+                request_envelope.to_address.ToString());
+
+      spdlog::info("got shard rsm message");
+
+      ShardMessages &&sm = std::move(conversion_attempt.value());
+      shard_manager_.Route(std::forward<ShardMessages>(sm), request_envelope.request_id, request_envelope.to_address,
+                           request_envelope.from_address);
+    }
+  }
+
+ private:
+  Time Cron() {
+    spdlog::info("running MachineManager::Cron, address {}", io_.GetAddress().ToString());
+    return shard_manager_.Cron();
+  }
+};
+
+}  // namespace memgraph::machine_manager

src/parser/CMakeLists.txt

@@ -0,0 +1,41 @@
+## Generate Antlr openCypher parser
+
+set(opencypher_frontend ${CMAKE_CURRENT_SOURCE_DIR}/opencypher)
+set(opencypher_generated ${opencypher_frontend}/generated)
+set(opencypher_lexer_grammar ${opencypher_frontend}/grammar/MemgraphCypherLexer.g4)
+set(opencypher_parser_grammar ${opencypher_frontend}/grammar/MemgraphCypher.g4)
+
+set(antlr_opencypher_generated_src
+    ${opencypher_generated}/MemgraphCypherLexer.cpp
+    ${opencypher_generated}/MemgraphCypher.cpp
+    ${opencypher_generated}/MemgraphCypherBaseVisitor.cpp
+    ${opencypher_generated}/MemgraphCypherVisitor.cpp
+)
+set(antlr_opencypher_generated_include
+    ${opencypher_generated}/MemgraphCypherLexer.h
+    ${opencypher_generated}/MemgraphCypher.h
+    ${opencypher_generated}/MemgraphCypherBaseVisitor.h
+    ${opencypher_generated}/MemgraphCypherVisitor.h
+)
+
+add_custom_command(
+    OUTPUT ${antlr_opencypher_generated_src} ${antlr_opencypher_generated_include}
+    COMMAND ${CMAKE_COMMAND} -E make_directory ${opencypher_generated}
+    COMMAND
+        java -jar ${CMAKE_SOURCE_DIR}/libs/antlr-4.10.1-complete.jar
+            -Dlanguage=Cpp -visitor -package antlropencypher
+            -o ${opencypher_generated}
+            ${opencypher_lexer_grammar} ${opencypher_parser_grammar}
+    WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
+    DEPENDS
+        ${opencypher_lexer_grammar} ${opencypher_parser_grammar}
+        ${opencypher_frontend}/grammar/CypherLexer.g4
+        ${opencypher_frontend}/grammar/Cypher.g4)
+
+add_custom_target(generated_opencypher_parser
+    DEPENDS ${antlr_opencypher_generated_src} ${antlr_opencypher_generated_include})
+
+add_library(mg-parser STATIC ${antlr_opencypher_generated_src})
+add_dependencies(mg-parser generated_opencypher_parser)
+target_include_directories(mg-parser PUBLIC ${CMAKE_CURRENT_SOURCE_DIR})
+target_link_libraries(mg-parser antlr4)

src/parser/opencypher/grammar/CypherLexer.g4

@@ -1,6 +1,6 @@
 /*
  * When changing this grammar make sure to update constants in
- * src/query/frontend/stripped_lexer_constants.hpp (kKeywords, kSpecialTokens
+ * src/parser/stripped_lexer_constants.hpp (kKeywords, kSpecialTokens
  * and bitsets) if needed.
  */
 

src/parser/opencypher/grammar/MemgraphCypher.g4

@@ -46,10 +46,10 @@ memgraphCypherKeyword : cypherKeyword
                       | DROP
                       | DUMP
                       | EXECUTE
-                      | FOR
-                      | FOREACH
                       | FREE
                       | FROM
+                      | FOR
+                      | FOREACH
                       | GLOBAL
                       | GRANT
                       | HEADER
@@ -76,6 +76,8 @@ memgraphCypherKeyword : cypherKeyword
                       | ROLE
                       | ROLES
                       | QUOTE
+                      | SCHEMA
+                      | SCHEMAS
                       | SESSION
                       | SETTING
                       | SETTINGS
@@ -122,6 +124,7 @@ query : cypherQuery
       | streamQuery
       | settingQuery
       | versionQuery
+      | schemaQuery
       ;
 
 authQuery : createRole
@@ -192,6 +195,12 @@ settingQuery : setSetting
              | showSettings
              ;
 
+schemaQuery : showSchema
+            | showSchemas
+            | createSchema
+            | dropSchema
+            ;
+
 loadCsv : LOAD CSV FROM csvFile ( WITH | NO ) HEADER
          ( IGNORE BAD ) ?
          ( DELIMITER delimiter ) ?
@@ -254,6 +263,7 @@ privilege : CREATE
           | MODULE_READ
           | MODULE_WRITE
           | WEBSOCKET
+          | SCHEMA
           ;
 
 privilegeList : privilege ( ',' privilege )* ;
@@ -276,7 +286,6 @@ replicaName : symbolicName ;
 socketAddress : literal ;
 
 registerReplica : REGISTER REPLICA replicaName ( SYNC | ASYNC )
-                ( WITH TIMEOUT timeout=literal ) ?
                 TO socketAddress ;
 
 dropReplica : DROP REPLICA replicaName ;
@@ -374,3 +383,17 @@ showSetting : SHOW DATABASE SETTING settingName ;
 showSettings : SHOW DATABASE SETTINGS ;
 
 versionQuery : SHOW VERSION ;
+
+showSchema : SHOW SCHEMA ON ':' labelName ;
+
+showSchemas : SHOW SCHEMAS ;
+
+propertyType : symbolicName ;
+
+propertyKeyTypePair : propertyKeyName propertyType ;
+
+schemaPropertyMap : '(' propertyKeyTypePair ( ',' propertyKeyTypePair )* ')' ;
+
+createSchema : CREATE SCHEMA ON ':' labelName schemaPropertyMap ;
+
+dropSchema : DROP SCHEMA ON ':' labelName ;

src/parser/opencypher/grammar/MemgraphCypherLexer.g4

@@ -15,7 +15,7 @@
 
 /*
  * When changing this grammar make sure to update constants in
- * src/query/frontend/stripped_lexer_constants.hpp (kKeywords, kSpecialTokens
+ * src/parser/stripped_lexer_constants.hpp (kKeywords, kSpecialTokens
  * and bitsets) if needed.
  */
 
@@ -89,6 +89,8 @@ REVOKE              : R E V O K E ;
 ROLE                : R O L E ;
 ROLES               : R O L E S ;
 QUOTE               : Q U O T E ;
+SCHEMA              : S C H E M A ;
+SCHEMAS             : S C H E M A S ;
 SERVICE_URL         : S E R V I C E UNDERSCORE U R L ;
 SESSION             : S E S S I O N ;
 SETTING             : S E T T I N G ;

src/parser/opencypher/parser.hpp

@@ -14,17 +14,29 @@
 #include <string>
 
 #include "antlr4-runtime.h"
-#include "query/v2/exceptions.hpp"
-#include "query/v2/frontend/opencypher/generated/MemgraphCypher.h"
-#include "query/v2/frontend/opencypher/generated/MemgraphCypherLexer.h"
+#include "utils/exceptions.hpp"
+#include "parser/opencypher/generated/MemgraphCypher.h"
+#include "parser/opencypher/generated/MemgraphCypherLexer.h"
+#include "utils/concepts.hpp"
 
-namespace memgraph::query::v2::frontend::opencypher {
+namespace memgraph::frontend::opencypher {
+
+class SyntaxException : public utils::BasicException {
+ public:
+  using utils::BasicException::BasicException;
+  SyntaxException() : SyntaxException("") {}
+};
 
 /**
  * Generates openCypher AST
  * This thing must me a class since parser.cypher() returns pointer and there is
  * no way for us to get ownership over the object.
  */
+enum class ParserOpTag : uint8_t {
+  CYPHER, EXPRESSION
+};
+
+template<ParserOpTag Tag = ParserOpTag::CYPHER>
 class Parser {
  public:
   /**
@@ -34,9 +46,14 @@ class Parser {
   Parser(const std::string query) : query_(std::move(query)) {
     parser_.removeErrorListeners();
     parser_.addErrorListener(&error_listener_);
-    tree_ = parser_.cypher();
+    if constexpr(Tag == ParserOpTag::CYPHER) {
+      tree_ = parser_.cypher();
+    }
+    else {
+      tree_ = parser_.expression();
+    }
     if (parser_.getNumberOfSyntaxErrors()) {
-      throw query::v2::SyntaxException(error_listener_.error_);
+      throw SyntaxException(error_listener_.error_);
     }
   }
 
@@ -65,4 +82,4 @@ class Parser {
   antlropencypher::MemgraphCypher parser_{&tokens_};
   antlr4::tree::ParseTree *tree_ = nullptr;
 };
-}  // namespace memgraph::query::v2::frontend::opencypher
+}  // namespace memgraph::frontend::opencypher

src/parser/stripped_lexer_constants.hpp

@@ -17,7 +17,7 @@
 #include <unordered_set>
 #include <vector>
 
-namespace memgraph::query::v2 {
+namespace parser {
 namespace lexer_constants {
 
 namespace trie {
@@ -204,8 +204,9 @@ const trie::Trie kKeywords = {"union",
                               "pulsar",
                               "service_url",
                               "version",
-                              "websocket"
-                              "foreach"};
+                              "websocket",
+                              "foreach",
+                              "schema"};
 
 // Unicode codepoints that are allowed at the start of the unescaped name.
 const std::bitset<kBitsetSize> kUnescapedNameAllowedStarts(
@@ -2921,4 +2922,4 @@ const trie::Trie kSpecialTokens = {";",
                                    "\xEF\xB9\xA3",   // u8"\ufe63"
                                    "\xEF\xBC\x8D"};  // u8"\uff0d"
 }  // namespace lexer_constants
-}  // namespace memgraph::query::v2
+}  // namespace parser

src/query/common.hpp

@@ -16,7 +16,6 @@
 #include <cstdint>
 #include <string>
 #include <string_view>
-#include <type_traits>
 
 #include "query/db_accessor.hpp"
 #include "query/exceptions.hpp"
@@ -25,12 +24,8 @@
 #include "query/typed_value.hpp"
 #include "storage/v2/id_types.hpp"
 #include "storage/v2/property_value.hpp"
-#include "storage/v2/result.hpp"
-#include "storage/v2/schema_validator.hpp"
 #include "storage/v2/view.hpp"
-#include "utils/exceptions.hpp"
 #include "utils/logging.hpp"
-#include "utils/variant_helpers.hpp"
 
 namespace memgraph::query {
 
@@ -86,79 +81,27 @@ concept AccessorWithSetProperty = requires(T accessor, const storage::PropertyId
   { accessor.SetProperty(key, new_value) } -> std::same_as<storage::Result<storage::PropertyValue>>;
 };
 
-inline void HandleSchemaViolation(const storage::SchemaViolation &schema_violation, const DbAccessor &dba) {
-  switch (schema_violation.status) {
-    case storage::SchemaViolation::ValidationStatus::VERTEX_HAS_NO_PRIMARY_PROPERTY: {
-      throw SchemaViolationException(
-          fmt::format("Primary key {} not defined on label :{}",
-                      storage::SchemaTypeToString(schema_violation.violated_schema_property->type),
-                      dba.LabelToName(schema_violation.label)));
-    }
-    case storage::SchemaViolation::ValidationStatus::NO_SCHEMA_DEFINED_FOR_LABEL: {
-      throw SchemaViolationException(
-          fmt::format("Label :{} is not a primary label", dba.LabelToName(schema_violation.label)));
-    }
-    case storage::SchemaViolation::ValidationStatus::VERTEX_PROPERTY_WRONG_TYPE: {
-      throw SchemaViolationException(
-          fmt::format("Wrong type of property {} in schema :{}, should be of type {}",
-                      *schema_violation.violated_property_value, dba.LabelToName(schema_violation.label),
-                      storage::SchemaTypeToString(schema_violation.violated_schema_property->type)));
-    }
-    case storage::SchemaViolation::ValidationStatus::VERTEX_UPDATE_PRIMARY_KEY: {
-      throw SchemaViolationException(fmt::format("Updating of primary key {} on schema :{} not supported",
-                                                 *schema_violation.violated_property_value,
-                                                 dba.LabelToName(schema_violation.label)));
-    }
-    case storage::SchemaViolation::ValidationStatus::VERTEX_MODIFY_PRIMARY_LABEL: {
-      throw SchemaViolationException(fmt::format("Cannot add or remove label :{} since it is a primary label",
-                                                 dba.LabelToName(schema_violation.label)));
-    }
-    case storage::SchemaViolation::ValidationStatus::VERTEX_SECONDARY_LABEL_IS_PRIMARY: {
-      throw SchemaViolationException(
-          fmt::format("Cannot create vertex with secondary label :{}", dba.LabelToName(schema_violation.label)));
-    }
-  }
-}
-
-inline void HandleErrorOnPropertyUpdate(const storage::Error error) {
-  switch (error) {
-    case storage::Error::SERIALIZATION_ERROR:
-      throw TransactionSerializationException();
-    case storage::Error::DELETED_OBJECT:
-      throw QueryRuntimeException("Trying to set properties on a deleted object.");
-    case storage::Error::PROPERTIES_DISABLED:
-      throw QueryRuntimeException("Can't set property because properties on edges are disabled.");
-    case storage::Error::VERTEX_HAS_EDGES:
-    case storage::Error::NONEXISTENT_OBJECT:
-      throw QueryRuntimeException("Unexpected error when setting a property.");
-  }
-}
-
 /// Set a property `value` mapped with given `key` on a `record`.
 ///
 /// @throw QueryRuntimeException if value cannot be set as a property value
 template <AccessorWithSetProperty T>
-storage::PropertyValue PropsSetChecked(T *record, const DbAccessor &dba, const storage::PropertyId &key,
-                                       const TypedValue &value) {
+storage::PropertyValue PropsSetChecked(T *record, const storage::PropertyId &key, const TypedValue &value) {
   try {
-    if constexpr (std::is_same_v<T, VertexAccessor>) {
-      const auto maybe_old_value = record->SetPropertyAndValidate(key, storage::PropertyValue(value));
-      if (maybe_old_value.HasError()) {
-        std::visit(utils::Overloaded{[](const storage::Error error) { HandleErrorOnPropertyUpdate(error); },
-                                     [&dba](const storage::SchemaViolation &schema_violation) {
-                                       HandleSchemaViolation(schema_violation, dba);
-                                     }},
-                   maybe_old_value.GetError());
+    auto maybe_old_value = record->SetProperty(key, storage::PropertyValue(value));
+    if (maybe_old_value.HasError()) {
+      switch (maybe_old_value.GetError()) {
+        case storage::Error::SERIALIZATION_ERROR:
+          throw TransactionSerializationException();
+        case storage::Error::DELETED_OBJECT:
+          throw QueryRuntimeException("Trying to set properties on a deleted object.");
+        case storage::Error::PROPERTIES_DISABLED:
+          throw QueryRuntimeException("Can't set property because properties on edges are disabled.");
+        case storage::Error::VERTEX_HAS_EDGES:
+        case storage::Error::NONEXISTENT_OBJECT:
+          throw QueryRuntimeException("Unexpected error when setting a property.");
       }
-      return std::move(*maybe_old_value);
-    } else {
-      // No validation on edge properties
-      const auto maybe_old_value = record->SetProperty(key, storage::PropertyValue(value));
-      if (maybe_old_value.HasError()) {
-        HandleErrorOnPropertyUpdate(maybe_old_value.GetError());
-      }
-      return std::move(*maybe_old_value);
     }
+    return std::move(*maybe_old_value);
   } catch (const TypedValueException &) {
     throw QueryRuntimeException("'{}' cannot be used as a property value.", value.type());
   }

src/query/db_accessor.hpp

@@ -12,7 +12,6 @@
 #pragma once
 
 #include <optional>
-#include <vector>
 
 #include <cppitertools/filter.hpp>
 #include <cppitertools/imap.hpp>
@@ -24,7 +23,7 @@
 
 ///////////////////////////////////////////////////////////
 // Our communication layer and query engine don't mix
-// very well on Centos because OpenSSL version available
+// very well on Centos because OpenSSL version avaialable
 // on Centos 7 include  libkrb5 which has brilliant macros
 // called TRUE and FALSE. For more detailed explanation go
 // to memgraph.cpp.
@@ -35,8 +34,6 @@
 // simply undefine those macros as we're sure that libkrb5
 // won't and can't be used anywhere in the query engine.
 #include "storage/v2/storage.hpp"
-#include "utils/logging.hpp"
-#include "utils/result.hpp"
 
 #undef FALSE
 #undef TRUE
@@ -105,18 +102,10 @@ class VertexAccessor final {
 
   auto Labels(storage::View view) const { return impl_.Labels(view); }
 
-  auto PrimaryLabel(storage::View view) const { return impl_.PrimaryLabel(view); }
-
   storage::Result<bool> AddLabel(storage::LabelId label) { return impl_.AddLabel(label); }
 
-  storage::ResultSchema<bool> AddLabelAndValidate(storage::LabelId label) { return impl_.AddLabelAndValidate(label); }
-
   storage::Result<bool> RemoveLabel(storage::LabelId label) { return impl_.RemoveLabel(label); }
 
-  storage::ResultSchema<bool> RemoveLabelAndValidate(storage::LabelId label) {
-    return impl_.RemoveLabelAndValidate(label);
-  }
-
   storage::Result<bool> HasLabel(storage::View view, storage::LabelId label) const {
     return impl_.HasLabel(label, view);
   }
@@ -131,13 +120,8 @@ class VertexAccessor final {
     return impl_.SetProperty(key, value);
   }
 
-  storage::ResultSchema<storage::PropertyValue> SetPropertyAndValidate(storage::PropertyId key,
-                                                                       const storage::PropertyValue &value) {
-    return impl_.SetPropertyAndValidate(key, value);
-  }
-
-  storage::ResultSchema<storage::PropertyValue> RemovePropertyAndValidate(storage::PropertyId key) {
-    return SetPropertyAndValidate(key, storage::PropertyValue{});
+  storage::Result<storage::PropertyValue> RemoveProperty(storage::PropertyId key) {
+    return SetProperty(key, storage::PropertyValue());
   }
 
   storage::Result<std::map<storage::PropertyId, storage::PropertyValue>> ClearProperties() {
@@ -263,18 +247,7 @@ class DbAccessor final {
     return VerticesIterable(accessor_->Vertices(label, property, lower, upper, view));
   }
 
-  // TODO Remove when query modules have been fixed
-  [[deprecated]] VertexAccessor InsertVertex() { return VertexAccessor(accessor_->CreateVertex()); }
-
-  storage::ResultSchema<VertexAccessor> InsertVertexAndValidate(
-      const storage::LabelId primary_label, const std::vector<storage::LabelId> &labels,
-      const std::vector<std::pair<storage::PropertyId, storage::PropertyValue>> &properties) {
-    auto maybe_vertex_acc = accessor_->CreateVertexAndValidate(primary_label, labels, properties);
-    if (maybe_vertex_acc.HasError()) {
-      return {std::move(maybe_vertex_acc.GetError())};
-    }
-    return VertexAccessor{maybe_vertex_acc.GetValue()};
-  }
+  VertexAccessor InsertVertex() { return VertexAccessor(accessor_->CreateVertex()); }
 
   storage::Result<EdgeAccessor> InsertEdge(VertexAccessor *from, VertexAccessor *to,
                                            const storage::EdgeTypeId &edge_type) {
@@ -332,7 +305,7 @@ class DbAccessor final {
       return std::optional<VertexAccessor>{};
     }
 
-    return {std::make_optional<VertexAccessor>(*value)};
+    return std::make_optional<VertexAccessor>(*value);
   }
 
   storage::PropertyId NameToProperty(const std::string_view name) { return accessor_->NameToProperty(name); }
@@ -381,10 +354,6 @@ class DbAccessor final {
   storage::IndicesInfo ListAllIndices() const { return accessor_->ListAllIndices(); }
 
   storage::ConstraintsInfo ListAllConstraints() const { return accessor_->ListAllConstraints(); }
-
-  const storage::SchemaValidator &GetSchemaValidator() const { return accessor_->GetSchemaValidator(); }
-
-  storage::SchemasInfo ListAllSchemas() const { return accessor_->ListAllSchemas(); }
 };
 
 }  // namespace memgraph::query

src/query/exceptions.hpp

@@ -224,12 +224,4 @@ class VersionInfoInMulticommandTxException : public QueryException {
       : QueryException("Version info query not allowed in multicommand transactions.") {}
 };
 
-/**
- * An exception for an illegal operation that violates schema
- */
-class SchemaViolationException : public QueryRuntimeException {
- public:
-  using QueryRuntimeException::QueryRuntimeException;
-};
-
 }  // namespace memgraph::query

src/query/frontend/ast/ast.lcp

@@ -17,7 +17,6 @@
 #include <variant>
 #include <vector>
 
-#include "common/types.hpp"
 #include "query/frontend/ast/ast_visitor.hpp"
 #include "query/frontend/semantic/symbol.hpp"
 #include "query/interpret/awesome_memgraph_functions.hpp"
@@ -134,15 +133,6 @@ cpp<#
     }
     cpp<#))
 
-
-(defun clone-schema-property-vector (source dest)
-    #>cpp
-    ${dest}.reserve(${source}.size());
-    for (const auto &[property_ix, property_type]: ${source}) {
-      ${dest}.emplace_back(storage->GetPropertyIx(property_ix.name), property_type);
-    }
-    cpp<#)
-
 ;; The following index structs serve as a decoupling point of AST from
 ;; concrete database types. All the names are collected in AstStorage, and can
 ;; be indexed through these instances. This means that we can create a vector
@@ -2263,7 +2253,7 @@ cpp<#
     (lcp:define-enum privilege
         (create delete match merge set remove index stats auth constraint
          dump replication durability read_file free_memory trigger config stream module_read module_write
-         websocket schema)
+         websocket)
       (:serialize))
     #>cpp
     AuthQuery() = default;
@@ -2305,7 +2295,7 @@ const std::vector<AuthQuery::Privilege> kPrivilegesAll = {
     AuthQuery::Privilege::FREE_MEMORY, AuthQuery::Privilege::TRIGGER,
     AuthQuery::Privilege::CONFIG,      AuthQuery::Privilege::STREAM,
     AuthQuery::Privilege::MODULE_READ, AuthQuery::Privilege::MODULE_WRITE,
-    AuthQuery::Privilege::WEBSOCKET,   AuthQuery::Privilege::SCHEMA};
+    AuthQuery::Privilege::WEBSOCKET};
 cpp<#
 
 (lcp:define-class info-query (query)
@@ -2675,38 +2665,5 @@ cpp<#
   (:serialize (:slk))
   (:clone))
 
-(lcp:define-class schema-query (query)
-  ((action "Action" :scope :public)
-   (label "LabelIx" :scope :public
-          :slk-load (lambda (member)
-                     #>cpp
-                     slk::Load(&self->${member}, reader, storage);
-                     cpp<#)
-          :clone (lambda (source dest)
-                   #>cpp
-                   ${dest} = storage->GetLabelIx(${source}.name);
-                   cpp<#))
-    (schema_type_map "std::vector<std::pair<PropertyIx, common::SchemaType>>"
-      :slk-save #'slk-save-property-map
-      :slk-load #'slk-load-property-map
-      :clone #'clone-schema-property-vector
-      :scope :public))
-
-  (:public
-    (lcp:define-enum action
-        (create-schema drop-schema show-schema show-schemas)
-      (:serialize))
-    #>cpp
-    SchemaQuery() = default;
-
-    DEFVISITABLE(QueryVisitor<void>);
-    cpp<#)
-  (:private
-    #>cpp
-    friend class AstStorage;
-    cpp<#)
-  (:serialize (:slk))
-  (:clone))
-
 (lcp:pop-namespace) ;; namespace query
 (lcp:pop-namespace) ;; namespace memgraph

src/query/frontend/ast/ast_visitor.hpp

@@ -94,7 +94,6 @@ class StreamQuery;
 class SettingQuery;
 class VersionQuery;
 class Foreach;
-class SchemaQuery;
 
 using TreeCompositeVisitor = utils::CompositeVisitor<
     SingleQuery, CypherUnion, NamedExpression, OrOperator, XorOperator, AndOperator, NotOperator, AdditionOperator,
@@ -126,9 +125,9 @@ class ExpressionVisitor
           None, ParameterLookup, Identifier, PrimitiveLiteral, RegexMatch> {};
 
 template <class TResult>
-class QueryVisitor : public utils::Visitor<TResult, CypherQuery, ExplainQuery, ProfileQuery, IndexQuery, AuthQuery,
-                                           InfoQuery, ConstraintQuery, DumpQuery, ReplicationQuery, LockPathQuery,
-                                           FreeMemoryQuery, TriggerQuery, IsolationLevelQuery, CreateSnapshotQuery,
-                                           StreamQuery, SettingQuery, VersionQuery, SchemaQuery> {};
+class QueryVisitor
+    : public utils::Visitor<TResult, CypherQuery, ExplainQuery, ProfileQuery, IndexQuery, AuthQuery, InfoQuery,
+                            ConstraintQuery, DumpQuery, ReplicationQuery, LockPathQuery, FreeMemoryQuery, TriggerQuery,
+                            IsolationLevelQuery, CreateSnapshotQuery, StreamQuery, SettingQuery, VersionQuery> {};
 
 }  // namespace memgraph::query

src/query/frontend/ast/cypher_main_visitor.cpp

@@ -17,7 +17,6 @@
 #include <cstring>
 #include <iterator>
 #include <limits>
-#include <ranges>
 #include <string>
 #include <tuple>
 #include <type_traits>
@@ -28,7 +27,6 @@
 
 #include <boost/preprocessor/cat.hpp>
 
-#include "common/types.hpp"
 #include "query/exceptions.hpp"
 #include "query/frontend/ast/ast.hpp"
 #include "query/frontend/ast/ast_visitor.hpp"
@@ -1349,7 +1347,6 @@ antlrcpp::Any CypherMainVisitor::visitPrivilege(MemgraphCypher::PrivilegeContext
   if (ctx->MODULE_READ()) return AuthQuery::Privilege::MODULE_READ;
   if (ctx->MODULE_WRITE()) return AuthQuery::Privilege::MODULE_WRITE;
   if (ctx->WEBSOCKET()) return AuthQuery::Privilege::WEBSOCKET;
-  if (ctx->SCHEMA()) return AuthQuery::Privilege::SCHEMA;
   LOG_FATAL("Should not get here - unknown privilege!");
 }
 
@@ -2356,93 +2353,6 @@ antlrcpp::Any CypherMainVisitor::visitForeach(MemgraphCypher::ForeachContext *ct
   return for_each;
 }
 
-antlrcpp::Any CypherMainVisitor::visitSchemaQuery(MemgraphCypher::SchemaQueryContext *ctx) {
-  MG_ASSERT(ctx->children.size() == 1, "SchemaQuery should have exactly one child!");
-  auto *schema_query = ctx->children[0]->accept(this).as<SchemaQuery *>();
-  query_ = schema_query;
-  return schema_query;
-}
-
-antlrcpp::Any CypherMainVisitor::visitShowSchema(MemgraphCypher::ShowSchemaContext *ctx) {
-  auto *schema_query = storage_->Create<SchemaQuery>();
-  schema_query->action_ = SchemaQuery::Action::SHOW_SCHEMA;
-  schema_query->label_ = AddLabel(ctx->labelName()->accept(this));
-  query_ = schema_query;
-  return schema_query;
-}
-
-antlrcpp::Any CypherMainVisitor::visitShowSchemas(MemgraphCypher::ShowSchemasContext * /*ctx*/) {
-  auto *schema_query = storage_->Create<SchemaQuery>();
-  schema_query->action_ = SchemaQuery::Action::SHOW_SCHEMAS;
-  query_ = schema_query;
-  return schema_query;
-}
-
-antlrcpp::Any CypherMainVisitor::visitPropertyType(MemgraphCypher::PropertyTypeContext *ctx) {
-  MG_ASSERT(ctx->symbolicName());
-  const auto property_type = utils::ToLowerCase(ctx->symbolicName()->accept(this).as<std::string>());
-  if (property_type == "bool") {
-    return common::SchemaType::BOOL;
-  }
-  if (property_type == "string") {
-    return common::SchemaType::STRING;
-  }
-  if (property_type == "integer") {
-    return common::SchemaType::INT;
-  }
-  if (property_type == "date") {
-    return common::SchemaType::DATE;
-  }
-  if (property_type == "duration") {
-    return common::SchemaType::DURATION;
-  }
-  if (property_type == "localdatetime") {
-    return common::SchemaType::LOCALDATETIME;
-  }
-  if (property_type == "localtime") {
-    return common::SchemaType::LOCALTIME;
-  }
-  throw SyntaxException("Property type must be one of the supported types!");
-}
-
-/**
- * @return Schema*
- */
-antlrcpp::Any CypherMainVisitor::visitSchemaPropertyMap(MemgraphCypher::SchemaPropertyMapContext *ctx) {
-  std::vector<std::pair<PropertyIx, common::SchemaType>> schema_property_map;
-  for (auto *property_key_pair : ctx->propertyKeyTypePair()) {
-    PropertyIx key = property_key_pair->propertyKeyName()->accept(this);
-    common::SchemaType type = property_key_pair->propertyType()->accept(this);
-    if (std::ranges::find_if(schema_property_map, [&key](const auto &elem) { return elem.first == key; }) !=
-        schema_property_map.end()) {
-      throw SemanticException("Same property name can't appear twice in a schema map.");
-    }
-    schema_property_map.emplace_back(key, type);
-  }
-  return schema_property_map;
-}
-
-antlrcpp::Any CypherMainVisitor::visitCreateSchema(MemgraphCypher::CreateSchemaContext *ctx) {
-  auto *schema_query = storage_->Create<SchemaQuery>();
-  schema_query->action_ = SchemaQuery::Action::CREATE_SCHEMA;
-  schema_query->label_ = AddLabel(ctx->labelName()->accept(this));
-  schema_query->schema_type_map_ =
-      ctx->schemaPropertyMap()->accept(this).as<std::vector<std::pair<PropertyIx, common::SchemaType>>>();
-  query_ = schema_query;
-  return schema_query;
-}
-
-/**
- * @return Schema*
- */
-antlrcpp::Any CypherMainVisitor::visitDropSchema(MemgraphCypher::DropSchemaContext *ctx) {
-  auto *schema_query = storage_->Create<SchemaQuery>();
-  schema_query->action_ = SchemaQuery::Action::DROP_SCHEMA;
-  schema_query->label_ = AddLabel(ctx->labelName()->accept(this));
-  query_ = schema_query;
-  return schema_query;
-}
-
 LabelIx CypherMainVisitor::AddLabel(const std::string &name) { return storage_->GetLabelIx(name); }
 
 PropertyIx CypherMainVisitor::AddProperty(const std::string &name) { return storage_->GetPropertyIx(name); }

src/query/frontend/ast/cypher_main_visitor.hpp

@@ -849,41 +849,6 @@ class CypherMainVisitor : public antlropencypher::MemgraphCypherBaseVisitor {
    */
   antlrcpp::Any visitForeach(MemgraphCypher::ForeachContext *ctx) override;
 
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitPropertyType(MemgraphCypher::PropertyTypeContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitSchemaPropertyMap(MemgraphCypher::SchemaPropertyMapContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitSchemaQuery(MemgraphCypher::SchemaQueryContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitShowSchema(MemgraphCypher::ShowSchemaContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitShowSchemas(MemgraphCypher::ShowSchemasContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitCreateSchema(MemgraphCypher::CreateSchemaContext *ctx) override;
-
-  /**
-   * @return Schema*
-   */
-  antlrcpp::Any visitDropSchema(MemgraphCypher::DropSchemaContext *ctx) override;
-
  public:
   Query *query() { return query_; }
   const static std::string kAnonPrefix;

src/query/frontend/opencypher/grammar/MemgraphCypher.g4

@@ -46,10 +46,10 @@ memgraphCypherKeyword : cypherKeyword
                       | DROP
                       | DUMP
                       | EXECUTE
-                      | FREE
-                      | FROM
                       | FOR
                       | FOREACH
+                      | FREE
+                      | FROM
                       | GLOBAL
                       | GRANT
                       | HEADER
@@ -76,8 +76,6 @@ memgraphCypherKeyword : cypherKeyword
                       | ROLE
                       | ROLES
                       | QUOTE
-                      | SCHEMA
-                      | SCHEMAS
                       | SESSION
                       | SETTING
                       | SETTINGS
@@ -124,7 +122,6 @@ query : cypherQuery
       | streamQuery
       | settingQuery
       | versionQuery
-      | schemaQuery
       ;
 
 authQuery : createRole
@@ -195,12 +192,6 @@ settingQuery : setSetting
              | showSettings
              ;
 
-schemaQuery : showSchema
-            | showSchemas
-            | createSchema
-            | dropSchema
-            ;
-
 loadCsv : LOAD CSV FROM csvFile ( WITH | NO ) HEADER
          ( IGNORE BAD ) ?
          ( DELIMITER delimiter ) ?
@@ -263,7 +254,6 @@ privilege : CREATE
           | MODULE_READ
           | MODULE_WRITE
           | WEBSOCKET
-          | SCHEMA
           ;
 
 privilegeList : privilege ( ',' privilege )* ;
@@ -383,17 +373,3 @@ showSetting : SHOW DATABASE SETTING settingName ;
 showSettings : SHOW DATABASE SETTINGS ;
 
 versionQuery : SHOW VERSION ;
-
-showSchema : SHOW SCHEMA ON ':' labelName ;
-
-showSchemas : SHOW SCHEMAS ;
-
-propertyType : symbolicName ;
-
-propertyKeyTypePair : propertyKeyName propertyType ;
-
-schemaPropertyMap : '(' propertyKeyTypePair ( ',' propertyKeyTypePair )* ')' ;
-
-createSchema : CREATE SCHEMA ON ':' labelName schemaPropertyMap ;
-
-dropSchema : DROP SCHEMA ON ':' labelName ;

src/query/frontend/opencypher/grammar/MemgraphCypherLexer.g4

@@ -89,8 +89,6 @@ REVOKE              : R E V O K E ;
 ROLE                : R O L E ;
 ROLES               : R O L E S ;
 QUOTE               : Q U O T E ;
-SCHEMA              : S C H E M A ;
-SCHEMAS             : S C H E M A S ;
 SERVICE_URL         : S E R V I C E UNDERSCORE U R L ;
 SESSION             : S E S S I O N ;
 SETTING             : S E T T I N G ;

src/query/frontend/semantic/required_privileges.cpp

@@ -80,8 +80,6 @@ class PrivilegeExtractor : public QueryVisitor<void>, public HierarchicalTreeVis
 
   void Visit(VersionQuery & /*version_query*/) override { AddPrivilege(AuthQuery::Privilege::STATS); }
 
-  void Visit(SchemaQuery & /*schema_query*/) override { AddPrivilege(AuthQuery::Privilege::SCHEMA); }
-
   bool PreVisit(Create & /*unused*/) override {
     AddPrivilege(AuthQuery::Privilege::CREATE);
     return false;

src/query/frontend/stripped_lexer_constants.hpp

@@ -205,8 +205,7 @@ const trie::Trie kKeywords = {"union",
                               "service_url",
                               "version",
                               "websocket",
-                              "foreach",
-                              "schema"};
+                              "foreach"};
 
 // Unicode codepoints that are allowed at the start of the unescaped name.
 const std::bitset<kBitsetSize> kUnescapedNameAllowedStarts(

src/query/interpreter.cpp

@@ -45,7 +45,6 @@
 #include "query/typed_value.hpp"
 #include "storage/v2/property_value.hpp"
 #include "storage/v2/replication/enums.hpp"
-#include "storage/v2/schemas.hpp"
 #include "utils/algorithm.hpp"
 #include "utils/csv_parsing.hpp"
 #include "utils/event_counter.hpp"
@@ -873,102 +872,6 @@ Callback HandleSettingQuery(SettingQuery *setting_query, const Parameters &param
   }
 }
 
-Callback HandleSchemaQuery(SchemaQuery *schema_query, InterpreterContext *interpreter_context,
-                           std::vector<Notification> *notifications) {
-  Callback callback;
-  switch (schema_query->action_) {
-    case SchemaQuery::Action::SHOW_SCHEMAS: {
-      callback.header = {"label", "primary_key"};
-      callback.fn = [interpreter_context]() {
-        auto *db = interpreter_context->db;
-        auto schemas_info = db->ListAllSchemas();
-        std::vector<std::vector<TypedValue>> results;
-        results.reserve(schemas_info.schemas.size());
-
-        for (const auto &[label_id, schema_types] : schemas_info.schemas) {
-          std::vector<TypedValue> schema_info_row;
-          schema_info_row.reserve(3);
-
-          schema_info_row.emplace_back(db->LabelToName(label_id));
-          std::vector<std::string> primary_key_properties;
-          primary_key_properties.reserve(schema_types.size());
-          std::transform(schema_types.begin(), schema_types.end(), std::back_inserter(primary_key_properties),
-                         [&db](const auto &schema_type) {
-                           return db->PropertyToName(schema_type.property_id) +
-                                  "::" + storage::SchemaTypeToString(schema_type.type);
-                         });
-
-          schema_info_row.emplace_back(utils::Join(primary_key_properties, ", "));
-          results.push_back(std::move(schema_info_row));
-        }
-        return results;
-      };
-      return callback;
-    }
-    case SchemaQuery::Action::SHOW_SCHEMA: {
-      callback.header = {"property_name", "property_type"};
-      callback.fn = [interpreter_context, primary_label = schema_query->label_]() {
-        auto *db = interpreter_context->db;
-        const auto label = db->NameToLabel(primary_label.name);
-        const auto schema = db->GetSchema(label);
-        std::vector<std::vector<TypedValue>> results;
-        if (schema) {
-          for (const auto &schema_property : schema->second) {
-            std::vector<TypedValue> schema_info_row;
-            schema_info_row.reserve(2);
-            schema_info_row.emplace_back(db->PropertyToName(schema_property.property_id));
-            schema_info_row.emplace_back(storage::SchemaTypeToString(schema_property.type));
-            results.push_back(std::move(schema_info_row));
-          }
-          return results;
-        }
-        throw QueryException(fmt::format("Schema on label :{} not found!", primary_label.name));
-      };
-      return callback;
-    }
-    case SchemaQuery::Action::CREATE_SCHEMA: {
-      auto schema_type_map = schema_query->schema_type_map_;
-      if (schema_query->schema_type_map_.empty()) {
-        throw SyntaxException("One or more types have to be defined in schema definition.");
-      }
-      callback.fn = [interpreter_context, primary_label = schema_query->label_,
-                     schema_type_map = std::move(schema_type_map)]() {
-        auto *db = interpreter_context->db;
-        const auto label = db->NameToLabel(primary_label.name);
-        std::vector<storage::SchemaProperty> schemas_types;
-        schemas_types.reserve(schema_type_map.size());
-        for (const auto &schema_type : schema_type_map) {
-          auto property_id = db->NameToProperty(schema_type.first.name);
-          schemas_types.push_back({property_id, schema_type.second});
-        }
-        if (!db->CreateSchema(label, schemas_types)) {
-          throw QueryException(fmt::format("Schema on label :{} already exists!", primary_label.name));
-        }
-        return std::vector<std::vector<TypedValue>>{};
-      };
-      notifications->emplace_back(SeverityLevel::INFO, NotificationCode::CREATE_SCHEMA,
-                                  fmt::format("Create schema on label :{}", schema_query->label_.name));
-      return callback;
-    }
-    case SchemaQuery::Action::DROP_SCHEMA: {
-      callback.fn = [interpreter_context, primary_label = schema_query->label_]() {
-        auto *db = interpreter_context->db;
-        const auto label = db->NameToLabel(primary_label.name);
-
-        if (!db->DropSchema(label)) {
-          throw QueryException(fmt::format("Schema on label :{} does not exist!", primary_label.name));
-        }
-
-        return std::vector<std::vector<TypedValue>>{};
-      };
-      notifications->emplace_back(SeverityLevel::INFO, NotificationCode::DROP_SCHEMA,
-                                  fmt::format("Dropped schema on label :{}", schema_query->label_.name));
-      return callback;
-    }
-  }
-  return callback;
-}
-
 // Struct for lazy pulling from a vector
 struct PullPlanVector {
   explicit PullPlanVector(std::vector<std::vector<TypedValue>> values) : values_(std::move(values)) {}
@@ -2163,32 +2066,6 @@ PreparedQuery PrepareConstraintQuery(ParsedQuery parsed_query, bool in_explicit_
                        RWType::NONE};
 }
 
-PreparedQuery PrepareSchemaQuery(ParsedQuery parsed_query, bool in_explicit_transaction,
-                                 InterpreterContext *interpreter_context, std::vector<Notification> *notifications) {
-  if (in_explicit_transaction) {
-    throw ConstraintInMulticommandTxException();
-  }
-  auto *schema_query = utils::Downcast<SchemaQuery>(parsed_query.query);
-  MG_ASSERT(schema_query);
-  auto callback = HandleSchemaQuery(schema_query, interpreter_context, notifications);
-
-  return PreparedQuery{std::move(callback.header), std::move(parsed_query.required_privileges),
-                       [handler = std::move(callback.fn), action = QueryHandlerResult::NOTHING,
-                        pull_plan = std::shared_ptr<PullPlanVector>(nullptr)](
-                           AnyStream *stream, std::optional<int> n) mutable -> std::optional<QueryHandlerResult> {
-                         if (!pull_plan) {
-                           auto results = handler();
-                           pull_plan = std::make_shared<PullPlanVector>(std::move(results));
-                         }
-
-                         if (pull_plan->Pull(stream, n)) {
-                           return action;
-                         }
-                         return std::nullopt;
-                       },
-                       RWType::NONE};
-}
-
 void Interpreter::BeginTransaction() {
   const auto prepared_query = PrepareTransactionQuery("BEGIN");
   prepared_query.query_handler(nullptr, {});
@@ -2322,9 +2199,6 @@ Interpreter::PrepareResult Interpreter::Prepare(const std::string &query_string,
       prepared_query = PrepareSettingQuery(std::move(parsed_query), in_explicit_transaction_, &*execution_db_accessor_);
     } else if (utils::Downcast<VersionQuery>(parsed_query.query)) {
       prepared_query = PrepareVersionQuery(std::move(parsed_query), in_explicit_transaction_);
-    } else if (utils::Downcast<SchemaQuery>(parsed_query.query)) {
-      prepared_query = PrepareSchemaQuery(std::move(parsed_query), in_explicit_transaction_, interpreter_context_,
-                                          &query_execution->notifications);
     } else {
       LOG_FATAL("Should not get here -- unknown query type!");
     }

src/query/metadata.cpp

@@ -38,8 +38,6 @@ constexpr std::string_view GetCodeString(const NotificationCode code) {
       return "CreateIndex"sv;
     case NotificationCode::CREATE_STREAM:
       return "CreateStream"sv;
-    case NotificationCode::CREATE_SCHEMA:
-      return "CreateSchema"sv;
     case NotificationCode::CHECK_STREAM:
       return "CheckStream"sv;
     case NotificationCode::CREATE_TRIGGER:
@@ -50,8 +48,6 @@ constexpr std::string_view GetCodeString(const NotificationCode code) {
       return "DropReplica"sv;
     case NotificationCode::DROP_INDEX:
       return "DropIndex"sv;
-    case NotificationCode::DROP_SCHEMA:
-      return "DropSchema"sv;
     case NotificationCode::DROP_STREAM:
       return "DropStream"sv;
     case NotificationCode::DROP_TRIGGER:
@@ -72,10 +68,6 @@ constexpr std::string_view GetCodeString(const NotificationCode code) {
       return "ReplicaPortWarning"sv;
     case NotificationCode::SET_REPLICA:
       return "SetReplica"sv;
-    case NotificationCode::SHOW_SCHEMA:
-      return "ShowSchema"sv;
-    case NotificationCode::SHOW_SCHEMAS:
-      return "ShowSchemas"sv;
     case NotificationCode::START_STREAM:
       return "StartStream"sv;
     case NotificationCode::START_ALL_STREAMS:

src/query/metadata.hpp

@@ -26,14 +26,12 @@ enum class SeverityLevel : uint8_t { INFO, WARNING };
 enum class NotificationCode : uint8_t {
   CREATE_CONSTRAINT,
   CREATE_INDEX,
-  CREATE_SCHEMA,
   CHECK_STREAM,
   CREATE_STREAM,
   CREATE_TRIGGER,
   DROP_CONSTRAINT,
   DROP_INDEX,
   DROP_REPLICA,
-  DROP_SCHEMA,
   DROP_STREAM,
   DROP_TRIGGER,
   EXISTANT_INDEX,
@@ -44,8 +42,6 @@ enum class NotificationCode : uint8_t {
   REPLICA_PORT_WARNING,
   REGISTER_REPLICA,
   SET_REPLICA,
-  SHOW_SCHEMA,
-  SHOW_SCHEMAS,
   START_STREAM,
   START_ALL_STREAMS,
   STOP_STREAM,

src/query/plan/operator.cpp

@@ -37,12 +37,7 @@
 #include "query/procedure/cypher_types.hpp"
 #include "query/procedure/mg_procedure_impl.hpp"
 #include "query/procedure/module.hpp"
-#include "query/typed_value.hpp"
-#include "storage/v2/id_types.hpp"
 #include "storage/v2/property_value.hpp"
-#include "storage/v2/result.hpp"
-#include "storage/v2/schema_validator.hpp"
-#include "storage/v2/schemas.hpp"
 #include "utils/algorithm.hpp"
 #include "utils/csv_parsing.hpp"
 #include "utils/event_counter.hpp"
@@ -57,7 +52,6 @@
 #include "utils/readable_size.hpp"
 #include "utils/string.hpp"
 #include "utils/temporal.hpp"
-#include "utils/variant_helpers.hpp"
 
 // macro for the default implementation of LogicalOperator::Accept
 // that accepts the visitor and visits it's input_ operator
@@ -180,56 +174,45 @@ CreateNode::CreateNode(const std::shared_ptr<LogicalOperator> &input, const Node
 
 // Creates a vertex on this GraphDb. Returns a reference to vertex placed on the
 // frame.
-VertexAccessor &CreateLocalVertexAtomically(const NodeCreationInfo &node_info, Frame *frame,
-                                            ExecutionContext &context) {
+VertexAccessor &CreateLocalVertex(const NodeCreationInfo &node_info, Frame *frame, ExecutionContext &context) {
   auto &dba = *context.db_accessor;
+  auto new_node = dba.InsertVertex();
+  context.execution_stats[ExecutionStats::Key::CREATED_NODES] += 1;
+  for (auto label : node_info.labels) {
+    auto maybe_error = new_node.AddLabel(label);
+    if (maybe_error.HasError()) {
+      switch (maybe_error.GetError()) {
+        case storage::Error::SERIALIZATION_ERROR:
+          throw TransactionSerializationException();
+        case storage::Error::DELETED_OBJECT:
+          throw QueryRuntimeException("Trying to set a label on a deleted node.");
+        case storage::Error::VERTEX_HAS_EDGES:
+        case storage::Error::PROPERTIES_DISABLED:
+        case storage::Error::NONEXISTENT_OBJECT:
+          throw QueryRuntimeException("Unexpected error when setting a label.");
+      }
+    }
+    context.execution_stats[ExecutionStats::Key::CREATED_LABELS] += 1;
+  }
   // Evaluator should use the latest accessors, as modified in this query, when
   // setting properties on new nodes.
   ExpressionEvaluator evaluator(frame, context.symbol_table, context.evaluation_context, context.db_accessor,
                                 storage::View::NEW);
-
-  std::vector<std::pair<storage::PropertyId, storage::PropertyValue>> properties;
+  // TODO: PropsSetChecked allocates a PropertyValue, make it use context.memory
+  // when we update PropertyValue with custom allocator.
   if (const auto *node_info_properties = std::get_if<PropertiesMapList>(&node_info.properties)) {
-    properties.reserve(node_info_properties->size());
     for (const auto &[key, value_expression] : *node_info_properties) {
-      properties.emplace_back(key, storage::PropertyValue(value_expression->Accept(evaluator)));
+      PropsSetChecked(&new_node, key, value_expression->Accept(evaluator));
     }
   } else {
-    auto property_map = evaluator.Visit(*std::get<ParameterLookup *>(node_info.properties)).ValueMap();
-    properties.reserve(property_map.size());
-
-    for (const auto &[key, value] : property_map) {
+    auto property_map = evaluator.Visit(*std::get<ParameterLookup *>(node_info.properties));
+    for (const auto &[key, value] : property_map.ValueMap()) {
       auto property_id = dba.NameToProperty(key);
-      properties.emplace_back(property_id, value);
+      PropsSetChecked(&new_node, property_id, value);
     }
   }
-  // TODO Remove later on since that will be enforced from grammar side
-  MG_ASSERT(!node_info.labels.empty(), "There must be at least one label!");
-  const auto primary_label = node_info.labels[0];
-  std::vector<storage::LabelId> secondary_labels(node_info.labels.begin() + 1, node_info.labels.end());
-  auto maybe_new_node = dba.InsertVertexAndValidate(primary_label, secondary_labels, properties);
-  if (maybe_new_node.HasError()) {
-    std::visit(utils::Overloaded{[&dba](const storage::SchemaViolation &schema_violation) {
-                                   HandleSchemaViolation(schema_violation, dba);
-                                 },
-                                 [](const storage::Error error) {
-                                   switch (error) {
-                                     case storage::Error::SERIALIZATION_ERROR:
-                                       throw TransactionSerializationException();
-                                     case storage::Error::DELETED_OBJECT:
-                                       throw QueryRuntimeException("Trying to set a label on a deleted node.");
-                                     case storage::Error::VERTEX_HAS_EDGES:
-                                     case storage::Error::PROPERTIES_DISABLED:
-                                     case storage::Error::NONEXISTENT_OBJECT:
-                                       throw QueryRuntimeException("Unexpected error when setting a label.");
-                                   }
-                                 }},
-               maybe_new_node.GetError());
-  }
 
-  context.execution_stats[ExecutionStats::Key::CREATED_NODES] += 1;
-
-  (*frame)[node_info.symbol] = *maybe_new_node;
+  (*frame)[node_info.symbol] = new_node;
   return (*frame)[node_info.symbol].ValueVertex();
 }
 
@@ -254,7 +237,7 @@ bool CreateNode::CreateNodeCursor::Pull(Frame &frame, ExecutionContext &context)
   SCOPED_PROFILE_OP("CreateNode");
 
   if (input_cursor_->Pull(frame, context)) {
-    auto created_vertex = CreateLocalVertexAtomically(self_.node_info_, &frame, context);
+    auto created_vertex = CreateLocalVertex(self_.node_info_, &frame, context);
     if (context.trigger_context_collector) {
       context.trigger_context_collector->RegisterCreatedObject(created_vertex);
     }
@@ -303,13 +286,13 @@ EdgeAccessor CreateEdge(const EdgeCreationInfo &edge_info, DbAccessor *dba, Vert
     auto &edge = *maybe_edge;
     if (const auto *properties = std::get_if<PropertiesMapList>(&edge_info.properties)) {
       for (const auto &[key, value_expression] : *properties) {
-        PropsSetChecked(&edge, *dba, key, value_expression->Accept(*evaluator));
+        PropsSetChecked(&edge, key, value_expression->Accept(*evaluator));
       }
     } else {
       auto property_map = evaluator->Visit(*std::get<ParameterLookup *>(edge_info.properties));
       for (const auto &[key, value] : property_map.ValueMap()) {
         auto property_id = dba->NameToProperty(key);
-        PropsSetChecked(&edge, *dba, property_id, value);
+        PropsSetChecked(&edge, property_id, value);
       }
     }
 
@@ -386,7 +369,7 @@ VertexAccessor &CreateExpand::CreateExpandCursor::OtherVertex(Frame &frame, Exec
     ExpectType(self_.node_info_.symbol, dest_node_value, TypedValue::Type::Vertex);
     return dest_node_value.ValueVertex();
   }
-  auto &created_vertex = CreateLocalVertexAtomically(self_.node_info_, &frame, context);
+  auto &created_vertex = CreateLocalVertex(self_.node_info_, &frame, context);
   if (context.trigger_context_collector) {
     context.trigger_context_collector->RegisterCreatedObject(created_vertex);
   }
@@ -2063,7 +2046,7 @@ bool SetProperty::SetPropertyCursor::Pull(Frame &frame, ExecutionContext &contex
 
   switch (lhs.type()) {
     case TypedValue::Type::Vertex: {
-      auto old_value = PropsSetChecked(&lhs.ValueVertex(), *context.db_accessor, self_.property_, rhs);
+      auto old_value = PropsSetChecked(&lhs.ValueVertex(), self_.property_, rhs);
       context.execution_stats[ExecutionStats::Key::UPDATED_PROPERTIES] += 1;
       if (context.trigger_context_collector) {
         // rhs cannot be moved because it was created with the allocator that is only valid during current pull
@@ -2073,7 +2056,7 @@ bool SetProperty::SetPropertyCursor::Pull(Frame &frame, ExecutionContext &contex
       break;
     }
     case TypedValue::Type::Edge: {
-      auto old_value = PropsSetChecked(&lhs.ValueEdge(), *context.db_accessor, self_.property_, rhs);
+      auto old_value = PropsSetChecked(&lhs.ValueEdge(), self_.property_, rhs);
       context.execution_stats[ExecutionStats::Key::UPDATED_PROPERTIES] += 1;
       if (context.trigger_context_collector) {
         // rhs cannot be moved because it was created with the allocator that is only valid during current pull
@@ -2227,7 +2210,7 @@ void SetPropertiesOnRecord(TRecordAccessor *record, const TypedValue &rhs, SetPr
     case TypedValue::Type::Map: {
       for (const auto &kv : rhs.ValueMap()) {
         auto key = context->db_accessor->NameToProperty(kv.first);
-        auto old_value = PropsSetChecked(record, *context->db_accessor, key, kv.second);
+        auto old_value = PropsSetChecked(record, key, kv.second);
         if (should_register_change) {
           register_set_property(std::move(old_value), key, kv.second);
         }
@@ -2311,31 +2294,22 @@ bool SetLabels::SetLabelsCursor::Pull(Frame &frame, ExecutionContext &context) {
   // Skip setting labels on Null (can occur in optional match).
   if (vertex_value.IsNull()) return true;
   ExpectType(self_.input_symbol_, vertex_value, TypedValue::Type::Vertex);
-
-  auto &dba = *context.db_accessor;
   auto &vertex = vertex_value.ValueVertex();
-  for (const auto label : self_.labels_) {
-    auto maybe_value = vertex.AddLabelAndValidate(label);
+  for (auto label : self_.labels_) {
+    auto maybe_value = vertex.AddLabel(label);
     if (maybe_value.HasError()) {
-      std::visit(utils::Overloaded{[](const storage::Error error) {
-                                     switch (error) {
-                                       case storage::Error::SERIALIZATION_ERROR:
-                                         throw TransactionSerializationException();
-                                       case storage::Error::DELETED_OBJECT:
-                                         throw QueryRuntimeException("Trying to set a label on a deleted node.");
-                                       case storage::Error::VERTEX_HAS_EDGES:
-                                       case storage::Error::PROPERTIES_DISABLED:
-                                       case storage::Error::NONEXISTENT_OBJECT:
-                                         throw QueryRuntimeException("Unexpected error when setting a label.");
-                                     }
-                                   },
-                                   [&dba](const storage::SchemaViolation schema_violation) {
-                                     HandleSchemaViolation(schema_violation, dba);
-                                   }},
-                 maybe_value.GetError());
+      switch (maybe_value.GetError()) {
+        case storage::Error::SERIALIZATION_ERROR:
+          throw TransactionSerializationException();
+        case storage::Error::DELETED_OBJECT:
+          throw QueryRuntimeException("Trying to set a label on a deleted node.");
+        case storage::Error::VERTEX_HAS_EDGES:
+        case storage::Error::PROPERTIES_DISABLED:
+        case storage::Error::NONEXISTENT_OBJECT:
+          throw QueryRuntimeException("Unexpected error when setting a label.");
+      }
     }
 
-    context.execution_stats[ExecutionStats::Key::CREATED_LABELS]++;
     if (context.trigger_context_collector && *maybe_value) {
       context.trigger_context_collector->RegisterSetVertexLabel(vertex, label);
     }
@@ -2378,11 +2352,26 @@ bool RemoveProperty::RemovePropertyCursor::Pull(Frame &frame, ExecutionContext &
   TypedValue lhs = self_.lhs_->expression_->Accept(evaluator);
 
   auto remove_prop = [property = self_.property_, &context](auto *record) {
-    auto old_value = PropsSetChecked(record, *context.db_accessor, property, TypedValue{});
+    auto maybe_old_value = record->RemoveProperty(property);
+    if (maybe_old_value.HasError()) {
+      switch (maybe_old_value.GetError()) {
+        case storage::Error::DELETED_OBJECT:
+          throw QueryRuntimeException("Trying to remove a property on a deleted graph element.");
+        case storage::Error::SERIALIZATION_ERROR:
+          throw TransactionSerializationException();
+        case storage::Error::PROPERTIES_DISABLED:
+          throw QueryRuntimeException(
+              "Can't remove property because properties on edges are "
+              "disabled.");
+        case storage::Error::VERTEX_HAS_EDGES:
+        case storage::Error::NONEXISTENT_OBJECT:
+          throw QueryRuntimeException("Unexpected error when removing property.");
+      }
+    }
 
     if (context.trigger_context_collector) {
       context.trigger_context_collector->RegisterRemovedObjectProperty(*record, property,
-                                                                       TypedValue(std::move(old_value)));
+                                                                       TypedValue(std::move(*maybe_old_value)));
     }
   };
 
@@ -2436,25 +2425,18 @@ bool RemoveLabels::RemoveLabelsCursor::Pull(Frame &frame, ExecutionContext &cont
   ExpectType(self_.input_symbol_, vertex_value, TypedValue::Type::Vertex);
   auto &vertex = vertex_value.ValueVertex();
   for (auto label : self_.labels_) {
-    auto maybe_value = vertex.RemoveLabelAndValidate(label);
+    auto maybe_value = vertex.RemoveLabel(label);
     if (maybe_value.HasError()) {
-      std::visit(
-          utils::Overloaded{[](const storage::Error error) {
-                              switch (error) {
-                                case storage::Error::SERIALIZATION_ERROR:
-                                  throw TransactionSerializationException();
-                                case storage::Error::DELETED_OBJECT:
-                                  throw QueryRuntimeException("Trying to remove labels from a deleted node.");
-                                case storage::Error::VERTEX_HAS_EDGES:
-                                case storage::Error::PROPERTIES_DISABLED:
-                                case storage::Error::NONEXISTENT_OBJECT:
-                                  throw QueryRuntimeException("Unexpected error when removing labels from a node.");
-                              }
-                            },
-                            [&context](const storage::SchemaViolation &schema_violation) {
-                              HandleSchemaViolation(schema_violation, *context.db_accessor);
-                            }},
-          maybe_value.GetError());
+      switch (maybe_value.GetError()) {
+        case storage::Error::SERIALIZATION_ERROR:
+          throw TransactionSerializationException();
+        case storage::Error::DELETED_OBJECT:
+          throw QueryRuntimeException("Trying to remove labels from a deleted node.");
+        case storage::Error::VERTEX_HAS_EDGES:
+        case storage::Error::PROPERTIES_DISABLED:
+        case storage::Error::NONEXISTENT_OBJECT:
+          throw QueryRuntimeException("Unexpected error when removing labels from a node.");
+      }
     }
 
     context.execution_stats[ExecutionStats::Key::DELETED_LABELS] += 1;

src/query/v2/CMakeLists.txt

@@ -1,7 +1,6 @@
 define_add_lcp(add_lcp_query lcp_query_v2_cpp_files generated_lcp_query_v2_files)
 
 add_lcp_query(frontend/ast/ast.lcp)
-add_lcp_query(frontend/semantic/symbol.lcp)
 add_lcp_query(plan/operator.lcp)
 
 add_custom_target(generate_lcp_query_v2 DEPENDS ${generated_lcp_query_v2_files})
@@ -11,14 +10,9 @@ set(mg_query_v2_sources
     common.cpp
     cypher_query_interpreter.cpp
     dump.cpp
-    frontend/ast/cypher_main_visitor.cpp
-    frontend/ast/pretty_print.cpp
-    frontend/parsing.cpp
     frontend/semantic/required_privileges.cpp
-    frontend/semantic/symbol_generator.cpp
     frontend/stripped.cpp
     interpret/awesome_memgraph_functions.cpp
-    interpret/eval.cpp
     interpreter.cpp
     metadata.cpp
     plan/operator.cpp
@@ -29,25 +23,28 @@ set(mg_query_v2_sources
     plan/rewrite/index_lookup.cpp
     plan/rule_based_planner.cpp
     plan/variable_start_planner.cpp
-    procedure/mg_procedure_impl.cpp
-    procedure/mg_procedure_helpers.cpp
-    procedure/module.cpp
-    procedure/py_module.cpp
+    #    procedure/mg_procedure_impl.cpp
+    #    procedure/mg_procedure_helpers.cpp
+    #    procedure/module.cpp
+    #    procedure/py_module.cpp
     serialization/property_value.cpp
-    stream/streams.cpp
-    stream/sources.cpp
-    stream/common.cpp
-    trigger.cpp
-    trigger_context.cpp
-    typed_value.cpp)
+    #    stream/streams.cpp
+    #    stream/sources.cpp
+    #    stream/common.cpp
+    #    trigger.cpp
+    #    trigger_context.cpp
+    bindings/typed_value.cpp
+    accessors.cpp)
 
 find_package(Boost REQUIRED)
 
 add_library(mg-query-v2 STATIC ${mg_query_v2_sources})
 add_dependencies(mg-query-v2 generate_lcp_query_v2)
 target_include_directories(mg-query-v2 PUBLIC ${CMAKE_SOURCE_DIR}/include)
+target_include_directories(mg-query-v2 PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/bindings)
 target_link_libraries(mg-query-v2 dl cppitertools Boost::headers)
 target_link_libraries(mg-query-v2 mg-integrations-pulsar mg-integrations-kafka mg-storage-v3 mg-license mg-utils mg-kvstore mg-memory)
+target_link_libraries(mg-query-v2 mg-expr)
 
 if(NOT "${MG_PYTHON_PATH}" STREQUAL "")
     set(Python3_ROOT_DIR "${MG_PYTHON_PATH}")
@@ -60,45 +57,3 @@ else()
 endif()
 
 target_link_libraries(mg-query-v2 Python3::Python)
-
-# Generate Antlr openCypher parser
-set(opencypher_frontend ${CMAKE_CURRENT_SOURCE_DIR}/frontend/opencypher)
-set(opencypher_generated ${opencypher_frontend}/generated)
-set(opencypher_lexer_grammar ${opencypher_frontend}/grammar/MemgraphCypherLexer.g4)
-set(opencypher_parser_grammar ${opencypher_frontend}/grammar/MemgraphCypher.g4)
-
-set(antlr_opencypher_generated_src
-    ${opencypher_generated}/MemgraphCypherLexer.cpp
-    ${opencypher_generated}/MemgraphCypher.cpp
-    ${opencypher_generated}/MemgraphCypherBaseVisitor.cpp
-    ${opencypher_generated}/MemgraphCypherVisitor.cpp
-)
-set(antlr_opencypher_generated_include
-    ${opencypher_generated}/MemgraphCypherLexer.h
-    ${opencypher_generated}/MemgraphCypher.h
-    ${opencypher_generated}/MemgraphCypherBaseVisitor.h
-    ${opencypher_generated}/MemgraphCypherVisitor.h
-)
-
-add_custom_command(
-    OUTPUT ${antlr_opencypher_generated_src} ${antlr_opencypher_generated_include}
-    COMMAND ${CMAKE_COMMAND} -E make_directory ${opencypher_generated}
-    COMMAND
-    java -jar ${CMAKE_SOURCE_DIR}/libs/antlr-4.10.1-complete.jar
-    -Dlanguage=Cpp -visitor -package antlropencypher
-    -o ${opencypher_generated}
-    ${opencypher_lexer_grammar} ${opencypher_parser_grammar}
-    WORKING_DIRECTORY "${CMAKE_BINARY_DIR}"
-    DEPENDS
-    ${opencypher_lexer_grammar} ${opencypher_parser_grammar}
-    ${opencypher_frontend}/grammar/CypherLexer.g4
-    ${opencypher_frontend}/grammar/Cypher.g4)
-
-add_custom_target(generate_opencypher_parser_v2
-    DEPENDS ${antlr_opencypher_generated_src} ${antlr_opencypher_generated_include})
-
-add_library(antlr_opencypher_parser_lib_v2 STATIC ${antlr_opencypher_generated_src})
-add_dependencies(antlr_opencypher_parser_lib_v2 generate_opencypher_parser_v2)
-target_link_libraries(antlr_opencypher_parser_lib_v2 antlr4)
-
-target_link_libraries(mg-query-v2 antlr_opencypher_parser_lib_v2)

src/query/v2/accessors.cpp

@@ -0,0 +1,75 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "query/v2/accessors.hpp"
+#include "query/v2/requests.hpp"
+
+namespace memgraph::query::v2::accessors {
+EdgeAccessor::EdgeAccessor(Edge edge, std::vector<std::pair<PropertyId, Value>> props)
+    : edge(std::move(edge)), properties(std::move(props)) {}
+
+uint64_t EdgeAccessor::EdgeType() const { return edge.type.id; }
+
+std::vector<std::pair<PropertyId, Value>> EdgeAccessor::Properties() const {
+  return properties;
+  //    std::map<std::string, TypedValue> res;
+  //    for (const auto &[name, value] : *properties) {
+  //      res[name] = ValueToTypedValue(value);
+  //    }
+  //    return res;
+}
+
+// NOLINTNEXTLINE(readability-convert-member-functions-to-static)
+Value EdgeAccessor::GetProperty(const std::string & /*prop_name*/) const {
+  // TODO(kostasrim) fix this
+  return {};
+}
+
+Edge EdgeAccessor::GetEdge() const { return edge; }
+
+VertexAccessor EdgeAccessor::To() const { return VertexAccessor(Vertex{edge.dst}, {}); }
+
+VertexAccessor EdgeAccessor::From() const { return VertexAccessor(Vertex{edge.src}, {}); }
+
+VertexAccessor::VertexAccessor(Vertex v, std::vector<std::pair<PropertyId, Value>> props)
+    : vertex(std::move(v)), properties(std::move(props)) {}
+
+std::vector<Label> VertexAccessor::Labels() const { return vertex.labels; }
+
+bool VertexAccessor::HasLabel(Label &label) const {
+  return std::find_if(vertex.labels.begin(), vertex.labels.end(),
+                      [label](const auto &l) { return l.id == label.id; }) != vertex.labels.end();
+}
+
+std::vector<std::pair<PropertyId, Value>> VertexAccessor::Properties() const {
+  //    std::map<std::string, TypedValue> res;
+  //    for (const auto &[name, value] : *properties) {
+  //      res[name] = ValueToTypedValue(value);
+  //    }
+  //    return res;
+  return properties;
+}
+
+Value VertexAccessor::GetProperty(PropertyId prop_id) const {
+  return std::find_if(properties.begin(), properties.end(), [&](auto &pr) { return prop_id == pr.first; })->second;
+  //    return ValueToTypedValue(properties[prop_name]);
+}
+
+// NOLINTNEXTLINE(readability-convert-member-functions-to-static)
+Value VertexAccessor::GetProperty(const std::string & /*prop_name*/) const {
+  // TODO(kostasrim) Add string mapping
+  return {};
+  //    return ValueToTypedValue(properties[prop_name]);
+}
+
+msgs::Vertex VertexAccessor::GetVertex() const { return vertex; }
+
+}  // namespace memgraph::query::v2::accessors

src/query/v2/accessors.hpp

@@ -0,0 +1,187 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include <optional>
+#include <utility>
+#include <vector>
+
+#include "query/exceptions.hpp"
+#include "query/v2/requests.hpp"
+#include "storage/v3/view.hpp"
+#include "utils/bound.hpp"
+#include "utils/exceptions.hpp"
+#include "utils/memory.hpp"
+#include "utils/memory_tracker.hpp"
+
+namespace memgraph::query::v2::accessors {
+
+using Value = memgraph::msgs::Value;
+using Edge = memgraph::msgs::Edge;
+using Vertex = memgraph::msgs::Vertex;
+using Label = memgraph::msgs::Label;
+using PropertyId = memgraph::msgs::PropertyId;
+
+class VertexAccessor;
+
+class EdgeAccessor final {
+ public:
+  EdgeAccessor(Edge edge, std::vector<std::pair<PropertyId, Value>> props);
+
+  uint64_t EdgeType() const;
+
+  std::vector<std::pair<PropertyId, Value>> Properties() const;
+
+  Value GetProperty(const std::string &prop_name) const;
+
+  Edge GetEdge() const;
+
+  // Dummy function
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
+  inline size_t CypherId() const { return 10; }
+
+  //  bool HasSrcAccessor const { return src == nullptr; }
+  //  bool HasDstAccessor const { return dst == nullptr; }
+
+  VertexAccessor To() const;
+  VertexAccessor From() const;
+
+  friend bool operator==(const EdgeAccessor &lhs, const EdgeAccessor &rhs) {
+    return lhs.edge == rhs.edge && lhs.properties == rhs.properties;
+  }
+
+  friend bool operator!=(const EdgeAccessor &lhs, const EdgeAccessor &rhs) { return !(lhs == rhs); }
+
+ private:
+  Edge edge;
+  std::vector<std::pair<PropertyId, Value>> properties;
+};
+
+class VertexAccessor final {
+ public:
+  using PropertyId = msgs::PropertyId;
+  using Label = msgs::Label;
+  VertexAccessor(Vertex v, std::vector<std::pair<PropertyId, Value>> props);
+
+  std::vector<Label> Labels() const;
+
+  bool HasLabel(Label &label) const;
+
+  std::vector<std::pair<PropertyId, Value>> Properties() const;
+
+  Value GetProperty(PropertyId prop_id) const;
+  Value GetProperty(const std::string &prop_name) const;
+
+  msgs::Vertex GetVertex() const;
+
+  // Dummy function
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
+  inline size_t CypherId() const { return 10; }
+
+  //  auto InEdges(storage::View view, const std::vector<storage::EdgeTypeId> &edge_types) const
+  //      -> storage::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.InEdges(view)))> {
+  //    auto maybe_edges = impl_.InEdges(view, edge_types);
+  //    if (maybe_edges.HasError()) return maybe_edges.GetError();
+  //    return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
+  //  }
+  //
+  //  auto InEdges(storage::View view) const { return InEdges(view, {}); }
+  //
+  //  auto InEdges(storage::View view, const std::vector<storage::EdgeTypeId> &edge_types, const VertexAccessor &dest)
+  //  const
+  //      -> storage::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.InEdges(view)))> {
+  //    auto maybe_edges = impl_.InEdges(view, edge_types, &dest.impl_);
+  //    if (maybe_edges.HasError()) return maybe_edges.GetError();
+  //    return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
+  //  }
+  //
+  //  auto OutEdges(storage::View view, const std::vector<storage::EdgeTypeId> &edge_types) const
+  //      -> storage::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.OutEdges(view)))> {
+  //    auto maybe_edges = impl_.OutEdges(view, edge_types);
+  //    if (maybe_edges.HasError()) return maybe_edges.GetError();
+  //    return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
+  //  }
+  //
+  //  auto OutEdges(storage::View view) const { return OutEdges(view, {}); }
+  //
+  //  auto OutEdges(storage::View view, const std::vector<storage::EdgeTypeId> &edge_types,
+  //                const VertexAccessor &dest) const
+  //      -> storage::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.OutEdges(view)))> {
+  //    auto maybe_edges = impl_.OutEdges(view, edge_types, &dest.impl_);
+  //    if (maybe_edges.HasError()) return maybe_edges.GetError();
+  //    return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
+  //  }
+
+  //  storage::Result<size_t> InDegree(storage::View view) const { return impl_.InDegree(view); }
+  //
+  //  storage::Result<size_t> OutDegree(storage::View view) const { return impl_.OutDegree(view); }
+  //
+
+  friend bool operator==(const VertexAccessor &lhs, const VertexAccessor &rhs) {
+    return lhs.vertex == rhs.vertex && lhs.properties == rhs.properties;
+  }
+
+  friend bool operator!=(const VertexAccessor &lhs, const VertexAccessor &rhs) { return !(lhs == rhs); }
+
+ private:
+  Vertex vertex;
+  std::vector<std::pair<PropertyId, Value>> properties;
+};
+
+// inline VertexAccessor EdgeAccessor::To() const { return VertexAccessor(impl_.ToVertex()); }
+
+// inline VertexAccessor EdgeAccessor::From() const { return VertexAccessor(impl_.FromVertex()); }
+
+// Highly mocked interface. Won't work if used.
+class Path {
+ public:
+  // Empty for now
+  explicit Path(const VertexAccessor & /*vertex*/, utils::MemoryResource *memory = utils::NewDeleteResource())
+      : mem(memory) {}
+
+  template <typename... TOthers>
+  explicit Path(const VertexAccessor &vertex, const TOthers &...others) {}
+
+  template <typename... TOthers>
+  Path(std::allocator_arg_t /*unused*/, utils::MemoryResource *memory, const VertexAccessor &vertex,
+       const TOthers &...others) {}
+
+  Path(const Path & /*other*/) {}
+
+  Path(const Path & /*other*/, utils::MemoryResource *memory) : mem(memory) {}
+
+  Path(Path && /*other*/) noexcept {}
+
+  Path(Path && /*other*/, utils::MemoryResource *memory) : mem(memory) {}
+  Path &operator=(const Path &path) {
+    if (this == &path) {
+      return *this;
+    }
+    return *this;
+  }
+
+  Path &operator=(Path &&path) noexcept {
+    if (this == &path) {
+      return *this;
+    }
+    return *this;
+  }
+
+  ~Path() {}
+
+  friend bool operator==(const Path & /*lhs*/, const Path & /*rhs*/) { return true; };
+  utils::MemoryResource *GetMemoryResource() { return mem; }
+
+ private:
+  utils::MemoryResource *mem = utils::NewDeleteResource();
+};
+}  // namespace memgraph::query::v2::accessors

src/query/v2/bindings/ast_visitor.hpp

@@ -0,0 +1,16 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/ast/ast_visitor.hpp"

src/query/v2/bindings/bindings.hpp

@@ -0,0 +1,15 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#define MG_AST_INCLUDE_PATH "query/v2/frontend/ast/ast.hpp"  // NOLINT(cppcoreguidelines-macro-usage)
+#define MG_INJECTED_NAMESPACE_NAME memgraph::query::v2       // NOLINT(cppcoreguidelines-macro-usage)

src/query/v2/bindings/cypher_main_visitor.hpp

@@ -0,0 +1,20 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/ast/cypher_main_visitor.hpp"
+
+namespace memgraph::query::v2 {
+using CypherMainVisitor = memgraph::expr::CypherMainVisitor;
+}  // namespace memgraph::query::v2

src/query/v2/bindings/eval.hpp

@@ -0,0 +1,44 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/interpret/eval.hpp"
+#include "query/v2/bindings/typed_value.hpp"
+#include "query/v2/context.hpp"
+#include "query/v2/conversions.hpp"
+#include "query/v2/db_accessor.hpp"
+#include "query/v2/requests.hpp"
+#include "storage/v3/conversions.hpp"
+#include "storage/v3/property_value.hpp"
+#include "storage/v3/view.hpp"
+
+namespace memgraph::query::v2 {
+
+inline const auto lam = [](const auto &val) { return ValueToTypedValue(val); };
+namespace detail {
+class Callable {
+ public:
+  auto operator()(const memgraph::storage::v3::PropertyValue &val) const {
+    return memgraph::storage::v3::PropertyToTypedValue<TypedValue>(val);
+  };
+  auto operator()(const msgs::Value &val) const { return ValueToTypedValue(val); };
+};
+
+}  // namespace detail
+using ExpressionEvaluator =
+    memgraph::expr::ExpressionEvaluator<TypedValue, memgraph::query::v2::EvaluationContext, DbAccessor,
+                                        storage::v3::View, storage::v3::LabelId, msgs::Value, detail::Callable,
+                                        memgraph::storage::v3::Error, memgraph::expr::QueryEngineTag>;
+
+}  // namespace memgraph::query::v2

src/query/v2/bindings/frame.hpp

@@ -0,0 +1,21 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "query/v2/bindings/typed_value.hpp"
+#include "expr/interpret/frame.hpp"
+
+namespace memgraph::query::v2 {
+using Frame = memgraph::expr::Frame<TypedValue>;
+} // namespace memgraph::query::v2

src/query/v2/bindings/pretty_print.hpp

@@ -11,13 +11,9 @@
 
 #pragma once
 
-#include <iostream>
+#include "query/v2/bindings/bindings.hpp"
 
-#include "query/v2/frontend/ast/ast.hpp"
+#include "expr/ast/pretty_print.hpp"
 
 namespace memgraph::query::v2 {
-
-void PrintExpression(Expression *expr, std::ostream *out);
-void PrintExpression(NamedExpression *expr, std::ostream *out);
-
 }  // namespace memgraph::query::v2

src/query/v2/bindings/symbol.hpp

@@ -0,0 +1,20 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/semantic/symbol.hpp"
+
+namespace memgraph::query::v2 {
+using Symbol = memgraph::expr::Symbol;
+} // namespace memgraph::query::v2

src/query/v2/bindings/symbol_generator.hpp

@@ -0,0 +1,16 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/semantic/symbol_generator.hpp"

src/query/v2/bindings/symbol_table.hpp

@@ -0,0 +1,20 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/semantic/symbol_table.hpp"
+
+namespace memgraph::query::v2 {
+using SymbolTable = memgraph::expr::SymbolTable;
+} // namespace memgraph::query::v2

src/query/v2/bindings/typed_value.cpp

@@ -0,0 +1,19 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#include "expr/typed_value.hpp"
+#include "query/v2/accessors.hpp"
+#include "query/v2/path.hpp"
+
+namespace memgraph::expr {
+namespace v2 = memgraph::query::v2;
+template class TypedValueT<v2::accessors::VertexAccessor, v2::accessors::EdgeAccessor, v2::accessors::Path>;
+}  // namespace memgraph::expr

src/query/v2/bindings/typed_value.hpp

@@ -0,0 +1,27 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+
+#include "query/v2/bindings/bindings.hpp"
+
+#include "expr/typed_value.hpp"
+#include "query/v2/accessors.hpp"
+
+namespace memgraph::expr {
+namespace v2 = memgraph::query::v2;
+extern template class memgraph::expr::TypedValueT<v2::accessors::VertexAccessor, v2::accessors::EdgeAccessor,
+                                                  v2::accessors::Path>;
+}  // namespace memgraph::expr
+namespace memgraph::query::v2 {
+using TypedValue =
+    memgraph::expr::TypedValueT<v2::accessors::VertexAccessor, v2::accessors::EdgeAccessor, v2::accessors::Path>;
+}  // namespace memgraph::query::v2

src/query/v2/common.hpp

@@ -16,16 +16,23 @@
 #include <cstdint>
 #include <string>
 #include <string_view>
+#include <type_traits>
 
+#include "query/v2/bindings/symbol.hpp"
+#include "query/v2/bindings/typed_value.hpp"
 #include "query/v2/db_accessor.hpp"
 #include "query/v2/exceptions.hpp"
 #include "query/v2/frontend/ast/ast.hpp"
-#include "query/v2/frontend/semantic/symbol.hpp"
-#include "query/v2/typed_value.hpp"
+#include "query/v2/path.hpp"
+#include "storage/v3/conversions.hpp"
 #include "storage/v3/id_types.hpp"
 #include "storage/v3/property_value.hpp"
+#include "storage/v3/result.hpp"
+#include "storage/v3/schema_validator.hpp"
 #include "storage/v3/view.hpp"
+#include "utils/exceptions.hpp"
 #include "utils/logging.hpp"
+#include "utils/variant_helpers.hpp"
 
 namespace memgraph::query::v2 {
 
@@ -81,28 +88,93 @@ concept AccessorWithSetProperty = requires(T accessor, const storage::v3::Proper
   { accessor.SetProperty(key, new_value) } -> std::same_as<storage::v3::Result<storage::v3::PropertyValue>>;
 };
 
+template <typename T>
+concept AccessorWithSetPropertyAndValidate = requires(T accessor, const storage::v3::PropertyId key,
+                                                      const storage::v3::PropertyValue new_value) {
+  {
+    accessor.SetPropertyAndValidate(key, new_value)
+    } -> std::same_as<storage::v3::ResultSchema<storage::v3::PropertyValue>>;
+};
+
+template <typename TRecordAccessor>
+concept RecordAccessor =
+    AccessorWithSetProperty<TRecordAccessor> || AccessorWithSetPropertyAndValidate<TRecordAccessor>;
+
+inline void HandleSchemaViolation(const storage::v3::SchemaViolation &schema_violation, const DbAccessor &dba) {
+  switch (schema_violation.status) {
+    case storage::v3::SchemaViolation::ValidationStatus::VERTEX_HAS_NO_PRIMARY_PROPERTY: {
+      throw SchemaViolationException(
+          fmt::format("Primary key {} not defined on label :{}",
+                      storage::v3::SchemaTypeToString(schema_violation.violated_schema_property->type),
+                      dba.LabelToName(schema_violation.label)));
+    }
+    case storage::v3::SchemaViolation::ValidationStatus::NO_SCHEMA_DEFINED_FOR_LABEL: {
+      throw SchemaViolationException(
+          fmt::format("Label :{} is not a primary label", dba.LabelToName(schema_violation.label)));
+    }
+    case storage::v3::SchemaViolation::ValidationStatus::VERTEX_PROPERTY_WRONG_TYPE: {
+      throw SchemaViolationException(
+          fmt::format("Wrong type of property {} in schema :{}, should be of type {}",
+                      *schema_violation.violated_property_value, dba.LabelToName(schema_violation.label),
+                      storage::v3::SchemaTypeToString(schema_violation.violated_schema_property->type)));
+    }
+    case storage::v3::SchemaViolation::ValidationStatus::VERTEX_UPDATE_PRIMARY_KEY: {
+      throw SchemaViolationException(fmt::format("Updating of primary key {} on schema :{} not supported",
+                                                 *schema_violation.violated_property_value,
+                                                 dba.LabelToName(schema_violation.label)));
+    }
+    case storage::v3::SchemaViolation::ValidationStatus::VERTEX_UPDATE_PRIMARY_LABEL: {
+      throw SchemaViolationException(fmt::format(
+          "Adding primary label as secondary or removing primary label:", *schema_violation.violated_property_value,
+          dba.LabelToName(schema_violation.label)));
+    }
+    case storage::v3::SchemaViolation::ValidationStatus::VERTEX_SECONDARY_LABEL_IS_PRIMARY: {
+      throw SchemaViolationException(fmt::format("Cannot create vertex where primary label is secondary:{}",
+                                                 dba.LabelToName(schema_violation.label)));
+    }
+  }
+}
+
+inline void HandleErrorOnPropertyUpdate(const storage::v3::Error error) {
+  switch (error) {
+    case storage::v3::Error::SERIALIZATION_ERROR:
+      throw TransactionSerializationException();
+    case storage::v3::Error::DELETED_OBJECT:
+      throw QueryRuntimeException("Trying to set properties on a deleted object.");
+    case storage::v3::Error::PROPERTIES_DISABLED:
+      throw QueryRuntimeException("Can't set property because properties on edges are disabled.");
+    case storage::v3::Error::VERTEX_HAS_EDGES:
+    case storage::v3::Error::NONEXISTENT_OBJECT:
+      throw QueryRuntimeException("Unexpected error when setting a property.");
+  }
+}
+
 /// Set a property `value` mapped with given `key` on a `record`.
 ///
 /// @throw QueryRuntimeException if value cannot be set as a property value
-template <AccessorWithSetProperty T>
-storage::v3::PropertyValue PropsSetChecked(T *record, const storage::v3::PropertyId &key, const TypedValue &value) {
+template <RecordAccessor T>
+storage::v3::PropertyValue PropsSetChecked(T *record, const DbAccessor &dba, const storage::v3::PropertyId &key,
+                                           const TypedValue &value) {
   try {
-    auto maybe_old_value = record->SetProperty(key, storage::v3::PropertyValue(value));
-    if (maybe_old_value.HasError()) {
-      switch (maybe_old_value.GetError()) {
-        case storage::v3::Error::SERIALIZATION_ERROR:
-          throw TransactionSerializationException();
-        case storage::v3::Error::DELETED_OBJECT:
-          throw QueryRuntimeException("Trying to set properties on a deleted object.");
-        case storage::v3::Error::PROPERTIES_DISABLED:
-          throw QueryRuntimeException("Can't set property because properties on edges are disabled.");
-        case storage::v3::Error::VERTEX_HAS_EDGES:
-        case storage::v3::Error::NONEXISTENT_OBJECT:
-          throw QueryRuntimeException("Unexpected error when setting a property.");
+    if constexpr (std::is_same_v<T, VertexAccessor>) {
+      const auto maybe_old_value = record->SetPropertyAndValidate(key, storage::v3::TypedToPropertyValue(value));
+      if (maybe_old_value.HasError()) {
+        std::visit(utils::Overloaded{[](const storage::v3::Error error) { HandleErrorOnPropertyUpdate(error); },
+                                     [&dba](const storage::v3::SchemaViolation &schema_violation) {
+                                       HandleSchemaViolation(schema_violation, dba);
+                                     }},
+                   maybe_old_value.GetError());
       }
+      return std::move(*maybe_old_value);
+    } else {
+      // No validation on edge properties
+      const auto maybe_old_value = record->SetProperty(key, storage::v3::TypedToPropertyValue(value));
+      if (maybe_old_value.HasError()) {
+        HandleErrorOnPropertyUpdate(maybe_old_value.GetError());
+      }
+      return std::move(*maybe_old_value);
     }
-    return std::move(*maybe_old_value);
-  } catch (const TypedValueException &) {
+  } catch (const expr::TypedValueException &) {
     throw QueryRuntimeException("'{}' cannot be used as a property value.", value.type());
   }
 }

src/query/v2/context.hpp

@@ -13,12 +13,13 @@
 
 #include <type_traits>
 
+#include "query/v2/bindings/symbol_table.hpp"
 #include "query/v2/common.hpp"
-#include "query/v2/frontend/semantic/symbol_table.hpp"
 #include "query/v2/metadata.hpp"
 #include "query/v2/parameters.hpp"
 #include "query/v2/plan/profile.hpp"
-#include "query/v2/trigger.hpp"
+//#include "query/v2/trigger.hpp"
+#include "query/v2/shard_request_manager.hpp"
 #include "utils/async_timer.hpp"
 
 namespace memgraph::query::v2 {
@@ -70,8 +71,9 @@ struct ExecutionContext {
   plan::ProfilingStats stats;
   plan::ProfilingStats *stats_root{nullptr};
   ExecutionStats execution_stats;
-  TriggerContextCollector *trigger_context_collector{nullptr};
+  //  TriggerContextCollector *trigger_context_collector{nullptr};
   utils::AsyncTimer timer;
+  std::unique_ptr<msgs::ShardRequestManagerInterface> shard_request_manager{nullptr};
 };
 
 static_assert(std::is_move_assignable_v<ExecutionContext>, "ExecutionContext must be move assignable!");

src/query/v2/conversions.hpp

@@ -0,0 +1,100 @@
+// Copyright 2022 Memgraph Ltd.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.txt; by using this file, you agree to be bound by the terms of the Business Source
+// License, and you may not use this file except in compliance with the Business Source License.
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0, included in the file
+// licenses/APL.txt.
+
+#pragma once
+#include "bindings/typed_value.hpp"
+#include "query/v2/accessors.hpp"
+#include "query/v2/requests.hpp"
+
+namespace memgraph::query::v2 {
+
+inline TypedValue ValueToTypedValue(const msgs::Value &value) {
+  using Value = msgs::Value;
+  switch (value.type) {
+    case Value::Type::Null:
+      return {};
+    case Value::Type::Bool:
+      return TypedValue(value.bool_v);
+    case Value::Type::Int64:
+      return TypedValue(value.int_v);
+    case Value::Type::Double:
+      return TypedValue(value.double_v);
+    case Value::Type::String:
+      return TypedValue(value.string_v);
+    case Value::Type::List: {
+      const auto &lst = value.list_v;
+      std::vector<TypedValue> dst;
+      dst.reserve(lst.size());
+      for (const auto &elem : lst) {
+        dst.push_back(ValueToTypedValue(elem));
+      }
+      return TypedValue(std::move(dst));
+    }
+    case Value::Type::Map: {
+      const auto &value_map = value.map_v;
+      std::map<std::string, TypedValue> dst;
+      for (const auto &[key, val] : value_map) {
+        dst[key] = ValueToTypedValue(val);
+      }
+      return TypedValue(std::move(dst));
+    }
+    case Value::Type::Vertex:
+      return TypedValue(accessors::VertexAccessor(value.vertex_v, {}));
+    case Value::Type::Edge:
+      return TypedValue(accessors::EdgeAccessor(value.edge_v, {}));
+    case Value::Type::Path:
+      break;
+  }
+  throw std::runtime_error("Incorrect type in conversion");
+}
+
+inline msgs::Value TypedValueToValue(const TypedValue &value) {
+  using Value = msgs::Value;
+  switch (value.type()) {
+    case TypedValue::Type::Null:
+      return {};
+    case TypedValue::Type::Bool:
+      return Value(value.ValueBool());
+    case TypedValue::Type::Int:
+      return Value(value.ValueInt());
+    case TypedValue::Type::Double:
+      return Value(value.ValueDouble());
+    case TypedValue::Type::String:
+      return Value(std::string(value.ValueString()));
+    case TypedValue::Type::List: {
+      const auto &lst = value.ValueList();
+      std::vector<Value> dst;
+      dst.reserve(lst.size());
+      for (const auto &elem : lst) {
+        dst.push_back(TypedValueToValue(elem));
+      }
+      return Value(std::move(dst));
+    }
+    case TypedValue::Type::Map: {
+      const auto &value_map = value.ValueMap();
+      std::map<std::string, Value> dst;
+      for (const auto &[key, val] : value_map) {
+        dst[std::string(key)] = TypedValueToValue(val);
+      }
+      return Value(std::move(dst));
+    }
+    case TypedValue::Type::Vertex:
+      return Value(value.ValueVertex().GetVertex());
+    case TypedValue::Type::Edge:
+      return Value(value.ValueEdge().GetEdge());
+    case TypedValue::Type::Path:
+    default:
+      break;
+  }
+  throw std::runtime_error("Incorrect type in conversion");
+}
+
+}  // namespace memgraph::query::v2

src/query/v2/cypher_query_interpreter.cpp

@@ -10,6 +10,7 @@
 // licenses/APL.txt.
 
 #include "query/v2/cypher_query_interpreter.hpp"
+#include "query/v2/bindings/symbol_generator.hpp"
 
 // NOLINTNEXTLINE (cppcoreguidelines-avoid-non-const-global-variables)
 DEFINE_HIDDEN_bool(query_cost_planner, true, "Use the cost-estimating query planner.");
@@ -46,7 +47,7 @@ ParsedQuery ParseQuery(const std::string &query_string, const std::map<std::stri
   auto hash = stripped_query.hash();
   auto accessor = cache->access();
   auto it = accessor.find(hash);
-  std::unique_ptr<frontend::opencypher::Parser> parser;
+  std::unique_ptr<memgraph::frontend::opencypher::Parser<>> parser;
 
   // Return a copy of both the AST storage and the query.
   CachedQuery result;
@@ -63,11 +64,11 @@ ParsedQuery ParseQuery(const std::string &query_string, const std::map<std::stri
 
   if (it == accessor.end()) {
     try {
-      parser = std::make_unique<frontend::opencypher::Parser>(stripped_query.query());
+      parser = std::make_unique<memgraph::frontend::opencypher::Parser<>>(stripped_query.query());
     } catch (const SyntaxException &e) {
       // There is a syntax exception in the stripped query. Re-run the parser
       // on the original query to get an appropriate error messsage.
-      parser = std::make_unique<frontend::opencypher::Parser>(query_string);
+      parser = std::make_unique<memgraph::frontend::opencypher::Parser<>>(query_string);
 
       // If an exception was not thrown here, the stripper messed something
       // up.
@@ -76,8 +77,8 @@ ParsedQuery ParseQuery(const std::string &query_string, const std::map<std::stri
 
     // Convert the ANTLR4 parse tree into an AST.
     AstStorage ast_storage;
-    frontend::ParsingContext context{true};
-    frontend::CypherMainVisitor visitor(context, &ast_storage);
+    expr::ParsingContext context{true};
+    memgraph::expr::CypherMainVisitor visitor(context, &ast_storage);
 
     visitor.visit(parser->tree());
 
@@ -119,7 +120,7 @@ std::unique_ptr<LogicalPlan> MakeLogicalPlan(AstStorage ast_storage, CypherQuery
                                              DbAccessor *db_accessor,
                                              const std::vector<Identifier *> &predefined_identifiers) {
   auto vertex_counts = plan::MakeVertexCountCache(db_accessor);
-  auto symbol_table = MakeSymbolTable(query, predefined_identifiers);
+  auto symbol_table = expr::MakeSymbolTable(query, predefined_identifiers);
   auto planning_context = plan::MakePlanningContext(&ast_storage, &symbol_table, query, &vertex_counts);
   auto [root, cost] = plan::MakeLogicalPlan(&planning_context, parameters, FLAGS_query_cost_planner);
   return std::make_unique<SingleNodeLogicalPlan>(std::move(root), cost, std::move(ast_storage),

src/query/v2/cypher_query_interpreter.hpp

@@ -11,11 +11,11 @@
 
 #pragma once
 
+#include "parser/opencypher/parser.hpp"
+#include "query/v2/bindings/cypher_main_visitor.hpp"
+#include "query/v2/bindings/symbol_table.hpp"
 #include "query/v2/config.hpp"
-#include "query/v2/frontend/ast/cypher_main_visitor.hpp"
-#include "query/v2/frontend/opencypher/parser.hpp"
 #include "query/v2/frontend/semantic/required_privileges.hpp"
-#include "query/v2/frontend/semantic/symbol_generator.hpp"
 #include "query/v2/frontend/stripped.hpp"
 #include "query/v2/plan/planner.hpp"
 #include "utils/flag_validation.hpp"

src/query/v2/db_accessor.hpp

@@ -11,19 +11,22 @@
 
 #pragma once
 
+#include <cstdint>
 #include <optional>
+#include <vector>
 
 #include <cppitertools/filter.hpp>
 #include <cppitertools/imap.hpp>
 
 #include "query/v2/exceptions.hpp"
 #include "storage/v3/id_types.hpp"
+#include "storage/v3/key_store.hpp"
 #include "storage/v3/property_value.hpp"
 #include "storage/v3/result.hpp"
 
 ///////////////////////////////////////////////////////////
 // Our communication layer and query engine don't mix
-// very well on Centos because OpenSSL version avaialable
+// very well on Centos because OpenSSL version available
 // on Centos 7 include  libkrb5 which has brilliant macros
 // called TRUE and FALSE. For more detailed explanation go
 // to memgraph.cpp.
@@ -34,6 +37,8 @@
 // simply undefine those macros as we're sure that libkrb5
 // won't and can't be used anywhere in the query engine.
 #include "storage/v3/storage.hpp"
+#include "utils/logging.hpp"
+#include "utils/result.hpp"
 
 #undef FALSE
 #undef TRUE
@@ -51,7 +56,6 @@ class EdgeAccessor final {
  public:
   storage::v3::EdgeAccessor impl_;
 
- public:
   explicit EdgeAccessor(storage::v3::EdgeAccessor impl) : impl_(std::move(impl)) {}
 
   bool IsVisible(storage::v3::View view) const { return impl_.IsVisible(view); }
@@ -99,16 +103,29 @@ class VertexAccessor final {
 
   static EdgeAccessor MakeEdgeAccessor(const storage::v3::EdgeAccessor impl) { return EdgeAccessor(impl); }
 
- public:
   explicit VertexAccessor(storage::v3::VertexAccessor impl) : impl_(impl) {}
 
   bool IsVisible(storage::v3::View view) const { return impl_.IsVisible(view); }
 
   auto Labels(storage::v3::View view) const { return impl_.Labels(view); }
 
-  storage::v3::Result<bool> AddLabel(storage::v3::LabelId label) { return impl_.AddLabel(label); }
+  auto PrimaryLabel(storage::v3::View view) const { return impl_.PrimaryLabel(view); }
 
-  storage::v3::Result<bool> RemoveLabel(storage::v3::LabelId label) { return impl_.RemoveLabel(label); }
+  auto PrimaryKey(storage::v3::View view) const { return impl_.PrimaryKey(view); }
+
+  storage::v3::ResultSchema<bool> AddLabel(storage::v3::LabelId label) { return impl_.AddLabelAndValidate(label); }
+
+  storage::v3::ResultSchema<bool> AddLabelAndValidate(storage::v3::LabelId label) {
+    return impl_.AddLabelAndValidate(label);
+  }
+
+  storage::v3::ResultSchema<bool> RemoveLabel(storage::v3::LabelId label) {
+    return impl_.RemoveLabelAndValidate(label);
+  }
+
+  storage::v3::ResultSchema<bool> RemoveLabelAndValidate(storage::v3::LabelId label) {
+    return impl_.RemoveLabelAndValidate(label);
+  }
 
   storage::v3::Result<bool> HasLabel(storage::v3::View view, storage::v3::LabelId label) const {
     return impl_.HasLabel(label, view);
@@ -121,13 +138,18 @@ class VertexAccessor final {
     return impl_.GetProperty(key, view);
   }
 
-  storage::v3::Result<storage::v3::PropertyValue> SetProperty(storage::v3::PropertyId key,
-                                                              const storage::v3::PropertyValue &value) {
-    return impl_.SetProperty(key, value);
+  storage::v3::ResultSchema<storage::v3::PropertyValue> SetProperty(storage::v3::PropertyId key,
+                                                                    const storage::v3::PropertyValue &value) {
+    return impl_.SetPropertyAndValidate(key, value);
   }
 
-  storage::v3::Result<storage::v3::PropertyValue> RemoveProperty(storage::v3::PropertyId key) {
-    return SetProperty(key, storage::v3::PropertyValue());
+  storage::v3::ResultSchema<storage::v3::PropertyValue> SetPropertyAndValidate(
+      storage::v3::PropertyId key, const storage::v3::PropertyValue &value) {
+    return impl_.SetPropertyAndValidate(key, value);
+  }
+
+  storage::v3::ResultSchema<storage::v3::PropertyValue> RemovePropertyAndValidate(storage::v3::PropertyId key) {
+    return SetPropertyAndValidate(key, storage::v3::PropertyValue{});
   }
 
   storage::v3::Result<std::map<storage::v3::PropertyId, storage::v3::PropertyValue>> ClearProperties() {
@@ -146,7 +168,8 @@ class VertexAccessor final {
   auto InEdges(storage::v3::View view, const std::vector<storage::v3::EdgeTypeId> &edge_types,
                const VertexAccessor &dest) const
       -> storage::v3::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.InEdges(view)))> {
-    auto maybe_edges = impl_.InEdges(view, edge_types, &dest.impl_);
+    const auto dest_id = dest.impl_.Id(view).GetValue();
+    auto maybe_edges = impl_.InEdges(view, edge_types, &dest_id);
     if (maybe_edges.HasError()) return maybe_edges.GetError();
     return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
   }
@@ -163,7 +186,8 @@ class VertexAccessor final {
   auto OutEdges(storage::v3::View view, const std::vector<storage::v3::EdgeTypeId> &edge_types,
                 const VertexAccessor &dest) const
       -> storage::v3::Result<decltype(iter::imap(MakeEdgeAccessor, *impl_.OutEdges(view)))> {
-    auto maybe_edges = impl_.OutEdges(view, edge_types, &dest.impl_);
+    const auto dest_id = dest.impl_.Id(view).GetValue();
+    auto maybe_edges = impl_.OutEdges(view, edge_types, &dest_id);
     if (maybe_edges.HasError()) return maybe_edges.GetError();
     return iter::imap(MakeEdgeAccessor, std::move(*maybe_edges));
   }
@@ -172,9 +196,8 @@ class VertexAccessor final {
 
   storage::v3::Result<size_t> OutDegree(storage::v3::View view) const { return impl_.OutDegree(view); }
 
-  int64_t CypherId() const { return impl_.Gid().AsInt(); }
-
-  storage::v3::Gid Gid() const noexcept { return impl_.Gid(); }
+  // TODO(jbajic) Fix Remove Gid
+  static int64_t CypherId() { return 1; }
 
   bool operator==(const VertexAccessor &v) const noexcept {
     static_assert(noexcept(impl_ == v.impl_));
@@ -184,14 +207,19 @@ class VertexAccessor final {
   bool operator!=(const VertexAccessor &v) const noexcept { return !(*this == v); }
 };
 
-inline VertexAccessor EdgeAccessor::To() const { return VertexAccessor(impl_.ToVertex()); }
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wnull-dereference"
+// NOLINTNEXTLINE(readability-convert-member-functions-to-static,clang-analyzer-core.NonNullParamChecker)
+inline VertexAccessor EdgeAccessor::To() const { return *static_cast<VertexAccessor *>(nullptr); }
 
-inline VertexAccessor EdgeAccessor::From() const { return VertexAccessor(impl_.FromVertex()); }
+// NOLINTNEXTLINE(readability-convert-member-functions-to-static,clang-analyzer-core.NonNullParamChecker)
+inline VertexAccessor EdgeAccessor::From() const { return *static_cast<VertexAccessor *>(nullptr); }
+#pragma clang diagnostic pop
 
 inline bool EdgeAccessor::IsCycle() const { return To() == From(); }
 
 class DbAccessor final {
-  storage::v3::Storage::Accessor *accessor_;
+  storage::v3::Shard::Accessor *accessor_;
 
   class VerticesIterable final {
     storage::v3::VerticesIterable iterable_;
@@ -223,16 +251,18 @@ class DbAccessor final {
   };
 
  public:
-  explicit DbAccessor(storage::v3::Storage::Accessor *accessor) : accessor_(accessor) {}
+  explicit DbAccessor(storage::v3::Shard::Accessor *accessor) : accessor_(accessor) {}
 
-  std::optional<VertexAccessor> FindVertex(storage::v3::Gid gid, storage::v3::View view) {
-    auto maybe_vertex = accessor_->FindVertex(gid, view);
+  // TODO(jbajic) Fix Remove Gid
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
+  std::optional<VertexAccessor> FindVertex(uint64_t /*unused*/) { return std::nullopt; }
+
+  std::optional<VertexAccessor> FindVertex(storage::v3::PrimaryKey &primary_key, storage::v3::View view) {
+    auto maybe_vertex = accessor_->FindVertex(primary_key, view);
     if (maybe_vertex) return VertexAccessor(*maybe_vertex);
     return std::nullopt;
   }
 
-  void FinalizeTransaction() { accessor_->FinalizeTransaction(); }
-
   VerticesIterable Vertices(storage::v3::View view) { return VerticesIterable(accessor_->Vertices(view)); }
 
   VerticesIterable Vertices(storage::v3::View view, storage::v3::LabelId label) {
@@ -254,17 +284,27 @@ class DbAccessor final {
     return VerticesIterable(accessor_->Vertices(label, property, lower, upper, view));
   }
 
-  VertexAccessor InsertVertex() { return VertexAccessor(accessor_->CreateVertex()); }
+  storage::v3::ResultSchema<VertexAccessor> InsertVertexAndValidate(
+      const storage::v3::LabelId primary_label, const std::vector<storage::v3::LabelId> &labels,
+      const std::vector<std::pair<storage::v3::PropertyId, storage::v3::PropertyValue>> &properties) {
+    auto maybe_vertex_acc = accessor_->CreateVertexAndValidate(primary_label, labels, properties);
+    if (maybe_vertex_acc.HasError()) {
+      return {std::move(maybe_vertex_acc.GetError())};
+    }
+    return VertexAccessor{maybe_vertex_acc.GetValue()};
+  }
 
   storage::v3::Result<EdgeAccessor> InsertEdge(VertexAccessor *from, VertexAccessor *to,
                                                const storage::v3::EdgeTypeId &edge_type) {
-    auto maybe_edge = accessor_->CreateEdge(&from->impl_, &to->impl_, edge_type);
+    static constexpr auto kDummyGid = storage::v3::Gid::FromUint(0);
+    auto maybe_edge = accessor_->CreateEdge(from->impl_.Id(storage::v3::View::NEW).GetValue(),
+                                            to->impl_.Id(storage::v3::View::NEW).GetValue(), edge_type, kDummyGid);
     if (maybe_edge.HasError()) return storage::v3::Result<EdgeAccessor>(maybe_edge.GetError());
     return EdgeAccessor(*maybe_edge);
   }
 
   storage::v3::Result<std::optional<EdgeAccessor>> RemoveEdge(EdgeAccessor *edge) {
-    auto res = accessor_->DeleteEdge(&edge->impl_);
+    auto res = accessor_->DeleteEdge(edge->impl_.FromVertex(), edge->impl_.ToVertex(), edge->impl_.Gid());
     if (res.HasError()) {
       return res.GetError();
     }
@@ -312,13 +352,18 @@ class DbAccessor final {
       return std::optional<VertexAccessor>{};
     }
 
-    return std::make_optional<VertexAccessor>(*value);
+    return {std::make_optional<VertexAccessor>(*value)};
   }
 
+  // TODO(jbajic) Query engine should have a map of labels, properties and edge
+  // types
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
   storage::v3::PropertyId NameToProperty(const std::string_view name) { return accessor_->NameToProperty(name); }
 
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
   storage::v3::LabelId NameToLabel(const std::string_view name) { return accessor_->NameToLabel(name); }
 
+  // NOLINTNEXTLINE(readability-convert-member-functions-to-static)
   storage::v3::EdgeTypeId NameToEdgeType(const std::string_view name) { return accessor_->NameToEdgeType(name); }
 
   const std::string &PropertyToName(storage::v3::PropertyId prop) const { return accessor_->PropertyToName(prop); }
@@ -329,7 +374,7 @@ class DbAccessor final {
 
   void AdvanceCommand() { accessor_->AdvanceCommand(); }
 
-  utils::BasicResult<storage::v3::ConstraintViolation, void> Commit() { return accessor_->Commit(); }
+  void Commit() { return accessor_->Commit(coordinator::Hlc{}); }
 
   void Abort() { accessor_->Abort(); }
 
@@ -360,7 +405,9 @@ class DbAccessor final {
 
   storage::v3::IndicesInfo ListAllIndices() const { return accessor_->ListAllIndices(); }
 
-  storage::v3::ConstraintsInfo ListAllConstraints() const { return accessor_->ListAllConstraints(); }
+  const storage::v3::SchemaValidator &GetSchemaValidator() const { return accessor_->GetSchemaValidator(); }
+
+  storage::v3::SchemasInfo ListAllSchemas() const { return accessor_->ListAllSchemas(); }
 };
 
 }  // namespace memgraph::query::v2

src/query/v2/discard_value_stream.hpp

@@ -13,7 +13,7 @@
 
 #include <vector>
 
-#include "query/v2/typed_value.hpp"
+#include "query/v2/bindings/typed_value.hpp"
 
 namespace memgraph::query::v2 {
 struct DiscardValueResultStream final {

src/query/v2/dump.cpp

@@ -21,10 +21,10 @@
 
 #include <fmt/format.h>
 
+#include "query/v2/bindings/typed_value.hpp"
 #include "query/v2/db_accessor.hpp"
 #include "query/v2/exceptions.hpp"
 #include "query/v2/stream.hpp"
-#include "query/v2/typed_value.hpp"
 #include "storage/v3/property_value.hpp"
 #include "storage/v3/storage.hpp"
 #include "utils/algorithm.hpp"
@@ -269,10 +269,6 @@ PullPlanDump::PullPlanDump(DbAccessor *dba)
                    CreateLabelIndicesPullChunk(),
                    // Dump all label property indices
                    CreateLabelPropertyIndicesPullChunk(),
-                   // Dump all existence constraints
-                   CreateExistenceConstraintsPullChunk(),
-                   // Dump all unique constraints
-                   CreateUniqueConstraintsPullChunk(),
                    // Create internal index for faster edge creation
                    CreateInternalIndexPullChunk(),
                    // Dump all vertices
@@ -364,60 +360,6 @@ PullPlanDump::PullChunk PullPlanDump::CreateLabelPropertyIndicesPullChunk() {
   };
 }
 
-PullPlanDump::PullChunk PullPlanDump::CreateExistenceConstraintsPullChunk() {
-  return [this, global_index = 0U](AnyStream *stream, std::optional<int> n) mutable -> std::optional<size_t> {
-    // Delay the construction of constraint vectors
-    if (!constraints_info_) {
-      constraints_info_.emplace(dba_->ListAllConstraints());
-    }
-
-    const auto &existence = constraints_info_->existence;
-    size_t local_counter = 0;
-    while (global_index < existence.size() && (!n || local_counter < *n)) {
-      const auto &constraint = existence[global_index];
-      std::ostringstream os;
-      DumpExistenceConstraint(&os, dba_, constraint.first, constraint.second);
-      stream->Result({TypedValue(os.str())});
-
-      ++global_index;
-      ++local_counter;
-    }
-
-    if (global_index == existence.size()) {
-      return local_counter;
-    }
-
-    return std::nullopt;
-  };
-}
-
-PullPlanDump::PullChunk PullPlanDump::CreateUniqueConstraintsPullChunk() {
-  return [this, global_index = 0U](AnyStream *stream, std::optional<int> n) mutable -> std::optional<size_t> {
-    // Delay the construction of constraint vectors
-    if (!constraints_info_) {
-      constraints_info_.emplace(dba_->ListAllConstraints());
-    }
-
-    const auto &unique = constraints_info_->unique;
-    size_t local_counter = 0;
-    while (global_index < unique.size() && (!n || local_counter < *n)) {
-      const auto &constraint = unique[global_index];
-      std::ostringstream os;
-      DumpUniqueConstraint(&os, dba_, constraint.first, constraint.second);
-      stream->Result({TypedValue(os.str())});
-
-      ++global_index;
-      ++local_counter;
-    }
-
-    if (global_index == unique.size()) {
-      return local_counter;
-    }
-
-    return std::nullopt;
-  };
-}
-
 PullPlanDump::PullChunk PullPlanDump::CreateInternalIndexPullChunk() {
   return [this](AnyStream *stream, std::optional<int>) mutable -> std::optional<size_t> {
     if (vertices_iterable_.begin() != vertices_iterable_.end()) {

src/query/v2/dump.hpp

@@ -32,7 +32,6 @@ struct PullPlanDump {
   query::v2::DbAccessor *dba_ = nullptr;
 
   std::optional<storage::v3::IndicesInfo> indices_info_ = std::nullopt;
-  std::optional<storage::v3::ConstraintsInfo> constraints_info_ = std::nullopt;
 
   using VertexAccessorIterable = decltype(std::declval<query::v2::DbAccessor>().Vertices(storage::v3::View::OLD));
   using VertexAccessorIterableIterator = decltype(std::declval<VertexAccessorIterable>().begin());
@@ -55,8 +54,6 @@ struct PullPlanDump {
 
   PullChunk CreateLabelIndicesPullChunk();
   PullChunk CreateLabelPropertyIndicesPullChunk();
-  PullChunk CreateExistenceConstraintsPullChunk();
-  PullChunk CreateUniqueConstraintsPullChunk();
   PullChunk CreateInternalIndexPullChunk();
   PullChunk CreateVertexPullChunk();
   PullChunk CreateEdgePullChunk();

src/query/v2/exceptions.hpp

@@ -224,4 +224,12 @@ class VersionInfoInMulticommandTxException : public QueryException {
       : QueryException("Version info query not allowed in multicommand transactions.") {}
 };
 
+/**
+ * An exception for an illegal operation that violates schema
+ */
+class SchemaViolationException : public QueryRuntimeException {
+ public:
+  using QueryRuntimeException::QueryRuntimeException;
+};
+
 }  // namespace memgraph::query::v2