From 4e5fe37dd6036bbedad940037972c66c687616e9 Mon Sep 17 00:00:00 2001
From: Matej Ferencevic <matej.ferencevic@memgraph.io>
Date: Tue, 9 Oct 2018 11:09:10 +0200
Subject: [PATCH] Remove virtual and pimpl from single node

Summary:
This diff removes: `SingleNodeRecoveryTransactions`, `TypemapPack`
It also removes virtual and/or pimpl from: `SingleNodeCounters`,
`StorageGcSingleNode`, `SingleNodeConcurrentIdMapper`,
accessors (revert D1510), transaction engine, `GraphDbAccessor`, `GraphDb`

Reviewers: msantl, teon.banek

Reviewed By: msantl, teon.banek

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1639
---
 src/CMakeLists.txt                            |   2 +-
 src/database/{ => distributed}/counters.hpp   |   0
 .../distributed/distributed_counters.hpp      |   2 +-
 .../distributed/distributed_graph_db.cpp      |   2 +-
 src/database/distributed/graph_db.hpp         |   6 +-
 ...{single_node_counters.hpp => counters.hpp} |   7 +-
 src/database/single_node/graph_db.cpp         | 343 +++---------------
 src/database/single_node/graph_db.hpp         |  96 ++---
 .../single_node/graph_db_accessor.hpp         |  29 +-
 src/durability/single_node/recovery.cpp       |  30 ++
 src/durability/single_node/recovery.hpp       |  21 +-
 src/memgraph.cpp                              |   2 +-
 src/mvcc/distributed/record.hpp               |   2 +-
 src/mvcc/single_node/record.hpp               |   2 +-
 .../concurrent_id_mapper.hpp                  |   0
 .../concurrent_id_mapper_single_node.hpp      |   2 +-
 .../concurrent_id_mapper_worker.hpp           |   2 +-
 src/storage/distributed/garbage_collector.hpp |   2 +-
 src/storage/distributed/storage_gc.hpp        |   2 +-
 ...ngle_node.hpp => concurrent_id_mapper.hpp} |  11 +-
 src/storage/single_node/edge_accessor.cpp     |   4 +-
 src/storage/single_node/garbage_collector.hpp |   2 +-
 src/storage/single_node/record_accessor.cpp   |  26 +-
 src/storage/single_node/record_accessor.hpp   |  70 +---
 src/storage/single_node/storage_gc.hpp        |  12 +-
 .../single_node/storage_gc_single_node.hpp    |  22 --
 src/storage/single_node/vertex_accessor.cpp   |  28 +-
 src/storage/single_node/vertex_accessor.hpp   |  12 -
 src/transactions/distributed/engine.hpp       | 111 ++++++
 .../distributed/engine_distributed.hpp        |   2 +-
 .../distributed/engine_single_node.hpp        |   2 +-
 src/transactions/engine.hpp                   | 114 +-----
 .../{engine_single_node.cpp => engine.cpp}    |  35 +-
 src/transactions/single_node/engine.hpp       |  71 ++++
 .../single_node/engine_single_node.hpp        |  56 ---
 tests/benchmark/expansion.cpp                 |   2 +-
 tests/benchmark/mvcc.cpp                      |   4 +-
 tests/benchmark/query/planner.cpp             |   6 +-
 tests/benchmark/tx_engine.cpp                 |   4 +-
 tests/feature_benchmark/kafka/benchmark.cpp   |   2 +-
 tests/manual/query_planner.cpp                |   2 +-
 tests/manual/repl.cpp                         |   2 +-
 tests/manual/single_query.cpp                 |   2 +-
 tests/property_based/random_graph.cpp         |   2 +-
 tests/unit/bfs_single_node.cpp                |   2 +-
 tests/unit/bolt_encoder.cpp                   |   2 +-
 .../unit/concurrent_id_mapper_single_node.cpp |   6 +-
 tests/unit/cypher_main_visitor.cpp            |   2 +-
 tests/unit/database_key_index.cpp             |  18 +-
 tests/unit/database_label_property_index.cpp  |  14 +-
 tests/unit/database_transaction_timeout.cpp   |   2 +-
 tests/unit/durability.cpp                     |  62 ++--
 tests/unit/graph_db.cpp                       |   2 +-
 tests/unit/graph_db_accessor.cpp              |  26 +-
 tests/unit/graph_db_accessor_index_api.cpp    |   4 +-
 tests/unit/interpreter.cpp                    |   2 +-
 tests/unit/mvcc.cpp                           |   8 +-
 tests/unit/mvcc_find_update_common.hpp        |   4 +-
 tests/unit/mvcc_gc.cpp                        |   6 +-
 tests/unit/mvcc_gc_common.hpp                 |   4 +-
 tests/unit/query_common.hpp                   |   2 +-
 tests/unit/query_cost_estimator.cpp           |   2 +-
 tests/unit/query_expression_evaluator.cpp     |   2 +-
 .../unit/query_plan_accumulate_aggregate.cpp  |  20 +-
 tests/unit/query_plan_bag_semantics.cpp       |  12 +-
 .../query_plan_create_set_remove_delete.cpp   |  62 ++--
 tests/unit/query_plan_edge_cases.cpp          |   2 +-
 tests/unit/query_plan_match_filter_return.cpp |  62 ++--
 tests/unit/query_semantic.cpp                 |   2 +-
 tests/unit/query_variable_start_planner.cpp   |  18 +-
 tests/unit/record_edge_vertex_accessor.cpp    |  24 +-
 tests/unit/state_delta.cpp                    |  16 +-
 tests/unit/transaction_engine_single_node.cpp |  12 +-
 tests/unit/typed_value.cpp                    |   2 +-
 tools/tests/mg_recovery_check.cpp             |   4 +-
 75 files changed, 661 insertions(+), 901 deletions(-)
 rename src/database/{ => distributed}/counters.hpp (100%)
 rename src/database/single_node/{single_node_counters.hpp => counters.hpp} (77%)
 rename src/storage/{common => distributed}/concurrent_id_mapper.hpp (100%)
 rename src/storage/single_node/{concurrent_id_mapper_single_node.hpp => concurrent_id_mapper.hpp} (86%)
 delete mode 100644 src/storage/single_node/storage_gc_single_node.hpp
 create mode 100644 src/transactions/distributed/engine.hpp
 rename src/transactions/single_node/{engine_single_node.cpp => engine.cpp} (72%)
 create mode 100644 src/transactions/single_node/engine.hpp
 delete mode 100644 src/transactions/single_node/engine_single_node.hpp

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 0de998382..df7584a9e 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -46,7 +46,7 @@ set(mg_single_node_sources
     storage/common/property_value_store.cpp
     storage/single_node/record_accessor.cpp
     storage/single_node/vertex_accessor.cpp
-    transactions/single_node/engine_single_node.cpp
+    transactions/single_node/engine.cpp
     memgraph_init.cpp
 )
 
diff --git a/src/database/counters.hpp b/src/database/distributed/counters.hpp
similarity index 100%
rename from src/database/counters.hpp
rename to src/database/distributed/counters.hpp
diff --git a/src/database/distributed/distributed_counters.hpp b/src/database/distributed/distributed_counters.hpp
index c83a83c5e..7ac12a6be 100644
--- a/src/database/distributed/distributed_counters.hpp
+++ b/src/database/distributed/distributed_counters.hpp
@@ -6,7 +6,7 @@
 #include <string>
 
 #include "data_structures/concurrent/concurrent_map.hpp"
-#include "database/counters.hpp"
+#include "database/distributed/counters.hpp"
 
 namespace communication::rpc {
 class Server;
diff --git a/src/database/distributed/distributed_graph_db.cpp b/src/database/distributed/distributed_graph_db.cpp
index f964c0b98..b33ba2d2a 100644
--- a/src/database/distributed/distributed_graph_db.cpp
+++ b/src/database/distributed/distributed_graph_db.cpp
@@ -25,7 +25,7 @@
 #include "durability/distributed/snapshooter.hpp"
 // TODO: Why do we depend on query here?
 #include "query/exceptions.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
+#include "storage/distributed/concurrent_id_mapper.hpp"
 #include "storage/distributed/concurrent_id_mapper_master.hpp"
 #include "storage/distributed/concurrent_id_mapper_worker.hpp"
 #include "storage/distributed/storage_gc_master.hpp"
diff --git a/src/database/distributed/graph_db.hpp b/src/database/distributed/graph_db.hpp
index a9d54ba01..6c3e8b575 100644
--- a/src/database/distributed/graph_db.hpp
+++ b/src/database/distributed/graph_db.hpp
@@ -5,16 +5,16 @@
 #include <memory>
 #include <vector>
 
-#include "database/counters.hpp"
+#include "database/distributed/counters.hpp"
 #include "durability/distributed/recovery.hpp"
 #include "durability/distributed/wal.hpp"
 #include "io/network/endpoint.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
 #include "storage/common/types.hpp"
+#include "storage/distributed/concurrent_id_mapper.hpp"
 #include "storage/distributed/storage.hpp"
 #include "storage/distributed/storage_gc.hpp"
 #include "storage/distributed/vertex_accessor.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 #include "utils/scheduler.hpp"
 
 namespace database {
diff --git a/src/database/single_node/single_node_counters.hpp b/src/database/single_node/counters.hpp
similarity index 77%
rename from src/database/single_node/single_node_counters.hpp
rename to src/database/single_node/counters.hpp
index 4e801868e..5cd681f2b 100644
--- a/src/database/single_node/single_node_counters.hpp
+++ b/src/database/single_node/counters.hpp
@@ -6,20 +6,19 @@
 #include <string>
 
 #include "data_structures/concurrent/concurrent_map.hpp"
-#include "database/counters.hpp"
 
 namespace database {
 
 /// Implementation for the single-node memgraph
-class SingleNodeCounters : public Counters {
+class Counters {
  public:
-  int64_t Get(const std::string &name) override {
+  int64_t Get(const std::string &name) {
     return counters_.access()
         .emplace(name, std::make_tuple(name), std::make_tuple(0))
         .first->second.fetch_add(1);
   }
 
-  void Set(const std::string &name, int64_t value) override {
+  void Set(const std::string &name, int64_t value) {
     auto name_counter_pair = counters_.access().emplace(
         name, std::make_tuple(name), std::make_tuple(value));
     if (!name_counter_pair.second) name_counter_pair.first->second.store(value);
diff --git a/src/database/single_node/graph_db.cpp b/src/database/single_node/graph_db.cpp
index bda854ab3..1fc079656 100644
--- a/src/database/single_node/graph_db.cpp
+++ b/src/database/single_node/graph_db.cpp
@@ -4,220 +4,26 @@
 
 #include <glog/logging.h>
 
+#include "database/single_node/counters.hpp"
 #include "database/single_node/graph_db_accessor.hpp"
-#include "database/single_node/single_node_counters.hpp"
 #include "durability/paths.hpp"
 #include "durability/single_node/recovery.hpp"
 #include "durability/single_node/snapshooter.hpp"
-#include "storage/single_node/concurrent_id_mapper_single_node.hpp"
-#include "storage/single_node/storage_gc_single_node.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "storage/single_node/concurrent_id_mapper.hpp"
+#include "storage/single_node/storage_gc.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "utils/file.hpp"
 
 namespace database {
 
-namespace {
-
-//////////////////////////////////////////////////////////////////////
-// RecordAccessor and GraphDbAccessor implementations
-//////////////////////////////////////////////////////////////////////
-
-template <class TRecord>
-class SingleNodeRecordAccessor final {
- public:
-  typename RecordAccessor<TRecord>::AddressT GlobalAddress(
-      const RecordAccessor<TRecord> &record_accessor) {
-    // TODO: This is still coupled to distributed storage, albeit loosely.
-    int worker_id = 0;
-    CHECK(record_accessor.is_local());
-    return storage::Address<mvcc::VersionList<TRecord>>(record_accessor.gid(),
-                                                        worker_id);
-  }
-
-  void SetOldNew(const RecordAccessor<TRecord> &record_accessor, TRecord **old,
-                 TRecord **newr) {
-    auto &dba = record_accessor.db_accessor();
-    const auto &address = record_accessor.address();
-    CHECK(record_accessor.is_local());
-    address.local()->find_set_old_new(dba.transaction(), old, newr);
-  }
-
-  TRecord *FindNew(const RecordAccessor<TRecord> &record_accessor) {
-    const auto &address = record_accessor.address();
-    auto &dba = record_accessor.db_accessor();
-    CHECK(address.is_local());
-    return address.local()->update(dba.transaction());
-  }
-
-  void ProcessDelta(const RecordAccessor<TRecord> &record_accessor,
-                    const database::StateDelta &delta) {
-    CHECK(record_accessor.is_local());
-    record_accessor.db_accessor().wal().Emplace(delta);
-  }
-
-  int64_t CypherId(const RecordAccessor<TRecord> &record_accessor) {
-    return record_accessor.address().local()->cypher_id();
-  }
-};
-
-class VertexAccessorImpl final : public ::VertexAccessor::Impl {
-  SingleNodeRecordAccessor<Vertex> accessor_;
-
- public:
-  typename RecordAccessor<Vertex>::AddressT GlobalAddress(
-      const RecordAccessor<Vertex> &ra) override {
-    return accessor_.GlobalAddress(ra);
-  }
-
-  void SetOldNew(const RecordAccessor<Vertex> &ra, Vertex **old_record,
-                 Vertex **new_record) override {
-    return accessor_.SetOldNew(ra, old_record, new_record);
-  }
-
-  Vertex *FindNew(const RecordAccessor<Vertex> &ra) override {
-    return accessor_.FindNew(ra);
-  }
-
-  void ProcessDelta(const RecordAccessor<Vertex> &ra,
-                    const database::StateDelta &delta) override {
-    return accessor_.ProcessDelta(ra, delta);
-  }
-
-  void AddLabel(const VertexAccessor &va,
-                const storage::Label &label) override {
-    CHECK(va.is_local());
-    auto &dba = va.db_accessor();
-    auto delta = StateDelta::AddLabel(dba.transaction_id(), va.gid(), label,
-                                      dba.LabelName(label));
-    Vertex &vertex = va.update();
-    // not a duplicate label, add it
-    if (!utils::Contains(vertex.labels_, label)) {
-      vertex.labels_.emplace_back(label);
-      dba.wal().Emplace(delta);
-      dba.UpdateLabelIndices(label, va, &vertex);
-    }
-  }
-
-  void RemoveLabel(const VertexAccessor &va,
-                   const storage::Label &label) override {
-    CHECK(va.is_local());
-    auto &dba = va.db_accessor();
-    auto delta = StateDelta::RemoveLabel(dba.transaction_id(), va.gid(), label,
-                                         dba.LabelName(label));
-    Vertex &vertex = va.update();
-    if (utils::Contains(vertex.labels_, label)) {
-      auto &labels = vertex.labels_;
-      auto found = std::find(labels.begin(), labels.end(), delta.label);
-      std::swap(*found, labels.back());
-      labels.pop_back();
-      dba.wal().Emplace(delta);
-    }
-  }
-
-  int64_t CypherId(const RecordAccessor<Vertex> &ra) override {
-    return accessor_.CypherId(ra);
-  }
-};
-
-class EdgeAccessorImpl final : public ::RecordAccessor<Edge>::Impl {
-  SingleNodeRecordAccessor<Edge> accessor_;
-
- public:
-  typename RecordAccessor<Edge>::AddressT GlobalAddress(
-      const RecordAccessor<Edge> &ra) override {
-    return accessor_.GlobalAddress(ra);
-  }
-
-  void SetOldNew(const RecordAccessor<Edge> &ra, Edge **old_record,
-                 Edge **new_record) override {
-    return accessor_.SetOldNew(ra, old_record, new_record);
-  }
-
-  Edge *FindNew(const RecordAccessor<Edge> &ra) override {
-    return accessor_.FindNew(ra);
-  }
-
-  void ProcessDelta(const RecordAccessor<Edge> &ra,
-                    const database::StateDelta &delta) override {
-    return accessor_.ProcessDelta(ra, delta);
-  }
-
-  int64_t CypherId(const RecordAccessor<Edge> &ra) override {
-    return accessor_.CypherId(ra);
-  }
-};
-
-class SingleNodeAccessor : public GraphDbAccessor {
-  // Shared implementations of record accessors.
-  static VertexAccessorImpl vertex_accessor_;
-  static EdgeAccessorImpl edge_accessor_;
-
- public:
-  explicit SingleNodeAccessor(GraphDb &db) : GraphDbAccessor(db) {}
-  SingleNodeAccessor(GraphDb &db, tx::TransactionId tx_id)
-      : GraphDbAccessor(db, tx_id) {}
-
-  ::VertexAccessor::Impl *GetVertexImpl() override { return &vertex_accessor_; }
-
-  ::RecordAccessor<Edge>::Impl *GetEdgeImpl() override {
-    return &edge_accessor_;
-  }
-};
-
-VertexAccessorImpl SingleNodeAccessor::vertex_accessor_;
-EdgeAccessorImpl SingleNodeAccessor::edge_accessor_;
-
-}  // namespace
-
-//////////////////////////////////////////////////////////////////////
-// SingleNode GraphDb implementation
-//////////////////////////////////////////////////////////////////////
-
-template <template <typename TId> class TMapper>
-struct TypemapPack {
-  template <typename... TMapperArgs>
-  explicit TypemapPack(TMapperArgs &... args)
-      : label(args...), edge_type(args...), property(args...) {}
-  // TODO this should also be garbage collected
-  TMapper<storage::Label> label;
-  TMapper<storage::EdgeType> edge_type;
-  TMapper<storage::Property> property;
-};
-
-namespace impl {
-
-class SingleNode {
- public:
-  explicit SingleNode(const Config &config) : config_(config) {}
-
-  Config config_;
-  std::unique_ptr<Storage> storage_ =
-      std::make_unique<Storage>(config_.worker_id, config_.properties_on_disk);
-  durability::WriteAheadLog wal_{
-      config_.worker_id, config_.durability_directory,
-      config_.durability_enabled, config_.synchronous_commit};
-
-  tx::EngineSingleNode tx_engine_{&wal_};
-  std::unique_ptr<StorageGcSingleNode> storage_gc_ =
-      std::make_unique<StorageGcSingleNode>(*storage_, tx_engine_,
-                                            config_.gc_cycle_sec);
-  TypemapPack<storage::SingleNodeConcurrentIdMapper> typemap_pack_{
-      storage_->PropertiesOnDisk()};
-  database::SingleNodeCounters counters_;
-};
-
-}  // namespace impl
-
-SingleNode::SingleNode(Config config)
-    : impl_(std::make_unique<impl::SingleNode>(config)) {
+GraphDb::GraphDb(Config config) : config_(config) {
   CHECK(config.worker_id == 0)
       << "Worker ID should only be set in distributed GraphDb";
-  if (impl_->config_.durability_enabled)
-    utils::CheckDir(impl_->config_.durability_directory);
+  if (config_.durability_enabled) utils::CheckDir(config_.durability_directory);
 
   // Durability recovery.
-  if (impl_->config_.db_recover_on_startup) {
-    CHECK(durability::VersionConsistency(impl_->config_.durability_directory))
+  if (config_.db_recover_on_startup) {
+    CHECK(durability::VersionConsistency(config_.durability_directory))
         << "Contents of durability directory are not compatible with the "
            "current version of Memgraph binary!";
 
@@ -226,112 +32,108 @@ SingleNode::SingleNode(Config config)
     durability::RecoveryData recovery_data;
 
     recovery_info = durability::RecoverOnlySnapshot(
-        impl_->config_.durability_directory, this, &recovery_data,
+        config_.durability_directory, this, &recovery_data,
         std::experimental::nullopt, 0);
 
     // Post-recovery setup and checking.
     if (recovery_info) {
       recovery_data.wal_tx_to_recover = recovery_info->wal_recovered;
-      SingleNodeRecoveryTransanctions recovery_transactions(this);
-      durability::RecoverWal(impl_->config_.durability_directory, this,
-                             &recovery_data, &recovery_transactions);
+      durability::RecoveryTransactions recovery_transactions(this);
+      durability::RecoverWal(config_.durability_directory, this, &recovery_data,
+                             &recovery_transactions);
       durability::RecoverIndexes(this, recovery_data.indexes);
     }
   }
 
-  if (impl_->config_.durability_enabled) {
+  if (config_.durability_enabled) {
     // move any existing snapshots or wal files to a deprecated folder.
-    if (!impl_->config_.db_recover_on_startup &&
-        durability::ContainsDurabilityFiles(
-            impl_->config_.durability_directory)) {
-      durability::MoveToBackup(impl_->config_.durability_directory);
+    if (!config_.db_recover_on_startup &&
+        durability::ContainsDurabilityFiles(config_.durability_directory)) {
+      durability::MoveToBackup(config_.durability_directory);
       LOG(WARNING) << "Since Memgraph was not supposed to recover on startup "
                       "and durability is enabled, your current durability "
                       "files will likely be overriden. To prevent important "
                       "data loss, Memgraph has stored those files into a "
                       ".backup directory inside durability directory";
     }
-    impl_->wal_.Init();
+    wal_.Init();
     snapshot_creator_ = std::make_unique<utils::Scheduler>();
     snapshot_creator_->Run(
-        "Snapshot", std::chrono::seconds(impl_->config_.snapshot_cycle_sec),
-        [this] {
+        "Snapshot", std::chrono::seconds(config_.snapshot_cycle_sec), [this] {
           auto dba = this->Access();
           this->MakeSnapshot(*dba);
         });
   }
 
   // Start transaction killer.
-  if (impl_->config_.query_execution_time_sec != -1) {
+  if (config_.query_execution_time_sec != -1) {
     transaction_killer_.Run(
         "TX killer",
-        std::chrono::seconds(std::max(
-            1, std::min(5, impl_->config_.query_execution_time_sec / 4))),
+        std::chrono::seconds(
+            std::max(1, std::min(5, config_.query_execution_time_sec / 4))),
         [this]() {
-          impl_->tx_engine_.LocalForEachActiveTransaction(
-              [this](tx::Transaction &t) {
-                if (t.creation_time() +
-                        std::chrono::seconds(
-                            impl_->config_.query_execution_time_sec) <
-                    std::chrono::steady_clock::now()) {
-                  t.set_should_abort();
-                };
-              });
+          tx_engine_.LocalForEachActiveTransaction([this](tx::Transaction &t) {
+            if (t.creation_time() +
+                    std::chrono::seconds(config_.query_execution_time_sec) <
+                std::chrono::steady_clock::now()) {
+              t.set_should_abort();
+            };
+          });
         });
   }
 }
 
-SingleNode::~SingleNode() {
+GraphDb::~GraphDb() {
   snapshot_creator_ = nullptr;
 
   is_accepting_transactions_ = false;
-  impl_->tx_engine_.LocalForEachActiveTransaction(
+  tx_engine_.LocalForEachActiveTransaction(
       [](auto &t) { t.set_should_abort(); });
 
-  if (impl_->config_.snapshot_on_exit) {
+  if (config_.snapshot_on_exit) {
     auto dba = this->Access();
     MakeSnapshot(*dba);
   }
 }
 
-std::unique_ptr<GraphDbAccessor> SingleNode::Access() {
+std::unique_ptr<GraphDbAccessor> GraphDb::Access() {
   // NOTE: We are doing a heap allocation to allow polymorphism. If this poses
   // performance issues, we may want to have a stack allocated GraphDbAccessor
   // which is constructed with a pointer to some global implementation struct
   // which contains only pure functions (without any state).
-  return std::make_unique<SingleNodeAccessor>(*this);
+  return std::unique_ptr<GraphDbAccessor>(new GraphDbAccessor(*this));
 }
 
-std::unique_ptr<GraphDbAccessor> SingleNode::Access(tx::TransactionId tx_id) {
-  return std::make_unique<SingleNodeAccessor>(*this, tx_id);
+std::unique_ptr<GraphDbAccessor> GraphDb::Access(tx::TransactionId tx_id) {
+  return std::unique_ptr<GraphDbAccessor>(new GraphDbAccessor(*this, tx_id));
 }
 
-Storage &SingleNode::storage() { return *impl_->storage_; }
+Storage &GraphDb::storage() { return *storage_; }
 
-durability::WriteAheadLog &SingleNode::wal() { return impl_->wal_; }
+durability::WriteAheadLog &GraphDb::wal() { return wal_; }
 
-tx::Engine &SingleNode::tx_engine() { return impl_->tx_engine_; }
+tx::Engine &GraphDb::tx_engine() { return tx_engine_; }
 
-storage::ConcurrentIdMapper<storage::Label> &SingleNode::label_mapper() {
-  return impl_->typemap_pack_.label;
+storage::ConcurrentIdMapper<storage::Label> &GraphDb::label_mapper() {
+  return label_mapper_;
 }
 
-storage::ConcurrentIdMapper<storage::EdgeType> &SingleNode::edge_type_mapper() {
-  return impl_->typemap_pack_.edge_type;
+storage::ConcurrentIdMapper<storage::EdgeType> &GraphDb::edge_type_mapper() {
+  return edge_mapper_;
 }
 
-storage::ConcurrentIdMapper<storage::Property> &SingleNode::property_mapper() {
-  return impl_->typemap_pack_.property;
+storage::ConcurrentIdMapper<storage::Property> &GraphDb::property_mapper() {
+  return property_mapper_;
 }
 
-database::Counters &SingleNode::counters() { return impl_->counters_; }
+database::Counters &GraphDb::counters() { return counters_; }
 
-void SingleNode::CollectGarbage() { impl_->storage_gc_->CollectGarbage(); }
+void GraphDb::CollectGarbage() { storage_gc_->CollectGarbage(); }
 
-bool SingleNode::MakeSnapshot(GraphDbAccessor &accessor) {
+bool GraphDb::MakeSnapshot(GraphDbAccessor &accessor) {
   const bool status = durability::MakeSnapshot(
-      *this, accessor, 0, fs::path(impl_->config_.durability_directory),
-      impl_->config_.snapshot_max_retained);
+      *this, accessor, 0, fs::path(config_.durability_directory),
+      config_.snapshot_max_retained);
   if (status) {
     LOG(INFO) << "Snapshot created successfully.";
   } else {
@@ -340,48 +142,13 @@ bool SingleNode::MakeSnapshot(GraphDbAccessor &accessor) {
   return status;
 }
 
-void SingleNode::ReinitializeStorage() {
+void GraphDb::ReinitializeStorage() {
   // Release gc scheduler to stop it from touching storage
-  impl_->storage_gc_ = nullptr;
-  impl_->storage_ = std::make_unique<Storage>(
-      impl_->config_.worker_id, impl_->config_.properties_on_disk);
-  impl_->storage_gc_ = std::make_unique<StorageGcSingleNode>(
-      *impl_->storage_, impl_->tx_engine_, impl_->config_.gc_cycle_sec);
-}
-
-SingleNodeRecoveryTransanctions::SingleNodeRecoveryTransanctions(SingleNode *db)
-    : db_(db) {}
-
-SingleNodeRecoveryTransanctions::~SingleNodeRecoveryTransanctions() {}
-
-void SingleNodeRecoveryTransanctions::Begin(const tx::TransactionId &tx_id) {
-  CHECK(accessors_.find(tx_id) == accessors_.end())
-      << "Double transaction start";
-  accessors_.emplace(tx_id, db_->Access());
-}
-
-GraphDbAccessor *GetAccessor(
-    const std::unordered_map<tx::TransactionId,
-                             std::unique_ptr<GraphDbAccessor>> &accessors,
-    const tx::TransactionId &tx_id) {
-  auto found = accessors.find(tx_id);
-  CHECK(found != accessors.end()) << "Accessor does not exist for transaction: "
-                                  << tx_id;
-  return found->second.get();
-}
-
-void SingleNodeRecoveryTransanctions::Abort(const tx::TransactionId &tx_id) {
-  GetAccessor(accessors_, tx_id)->Abort();
-  accessors_.erase(accessors_.find(tx_id));
-}
-
-void SingleNodeRecoveryTransanctions::Commit(const tx::TransactionId &tx_id) {
-  GetAccessor(accessors_, tx_id)->Commit();
-  accessors_.erase(accessors_.find(tx_id));
-}
-
-void SingleNodeRecoveryTransanctions::Apply(const database::StateDelta &delta) {
-  delta.Apply(*GetAccessor(accessors_, delta.transaction_id));
+  storage_gc_ = nullptr;
+  storage_ =
+      std::make_unique<Storage>(config_.worker_id, config_.properties_on_disk);
+  storage_gc_ =
+      std::make_unique<StorageGc>(*storage_, tx_engine_, config_.gc_cycle_sec);
 }
 
 }  // namespace database
diff --git a/src/database/single_node/graph_db.hpp b/src/database/single_node/graph_db.hpp
index 1241dd7c6..ba99ba124 100644
--- a/src/database/single_node/graph_db.hpp
+++ b/src/database/single_node/graph_db.hpp
@@ -5,15 +5,15 @@
 #include <memory>
 #include <vector>
 
-#include "database/counters.hpp"
+#include "database/single_node/counters.hpp"
 #include "durability/single_node/recovery.hpp"
 #include "durability/single_node/wal.hpp"
 #include "io/network/endpoint.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
 #include "storage/common/types.hpp"
+#include "storage/single_node/concurrent_id_mapper.hpp"
 #include "storage/single_node/storage.hpp"
 #include "storage/single_node/storage_gc.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "utils/scheduler.hpp"
 
 namespace database {
@@ -73,91 +73,63 @@ class GraphDbAccessor;
 /// -> CRASH
 class GraphDb {
  public:
-  GraphDb() {}
+  explicit GraphDb(Config config = Config());
+  ~GraphDb();
+
   GraphDb(const GraphDb &) = delete;
   GraphDb(GraphDb &&) = delete;
   GraphDb &operator=(const GraphDb &) = delete;
   GraphDb &operator=(GraphDb &&) = delete;
 
-  virtual ~GraphDb() {}
-
   /// Create a new accessor by starting a new transaction.
-  virtual std::unique_ptr<GraphDbAccessor> Access() = 0;
+  std::unique_ptr<GraphDbAccessor> Access();
   /// Create an accessor for a running transaction.
-  virtual std::unique_ptr<GraphDbAccessor> Access(tx::TransactionId) = 0;
+  std::unique_ptr<GraphDbAccessor> Access(tx::TransactionId);
 
-  virtual Storage &storage() = 0;
-  virtual durability::WriteAheadLog &wal() = 0;
-  virtual tx::Engine &tx_engine() = 0;
-  virtual storage::ConcurrentIdMapper<storage::Label> &label_mapper() = 0;
-  virtual storage::ConcurrentIdMapper<storage::EdgeType>
-      &edge_type_mapper() = 0;
-  virtual storage::ConcurrentIdMapper<storage::Property> &property_mapper() = 0;
-  virtual database::Counters &counters() = 0;
-  virtual void CollectGarbage() = 0;
+  Storage &storage();
+  durability::WriteAheadLog &wal();
+  tx::Engine &tx_engine();
+  storage::ConcurrentIdMapper<storage::Label> &label_mapper();
+  storage::ConcurrentIdMapper<storage::EdgeType> &edge_type_mapper();
+  storage::ConcurrentIdMapper<storage::Property> &property_mapper();
+  database::Counters &counters();
+  void CollectGarbage();
 
   /// Makes a snapshot from the visibility of the given accessor
-  virtual bool MakeSnapshot(GraphDbAccessor &accessor) = 0;
+  bool MakeSnapshot(GraphDbAccessor &accessor);
 
   /// Releases the storage object safely and creates a new object.
   /// This is needed because of recovery, otherwise we might try to recover into
   /// a storage which has already been polluted because of a failed previous
   /// recovery
-  virtual void ReinitializeStorage() = 0;
+  void ReinitializeStorage();
 
   /// When this is false, no new transactions should be created.
   bool is_accepting_transactions() const { return is_accepting_transactions_; }
 
  protected:
   std::atomic<bool> is_accepting_transactions_{true};
-};
-
-namespace impl {
-class SingleNode;
-}  // namespace impl
-
-class SingleNode final : public GraphDb {
- public:
-  explicit SingleNode(Config config = Config());
-  ~SingleNode();
-
-  std::unique_ptr<GraphDbAccessor> Access() override;
-  std::unique_ptr<GraphDbAccessor> Access(tx::TransactionId) override;
-
-  Storage &storage() override;
-  durability::WriteAheadLog &wal() override;
-  tx::Engine &tx_engine() override;
-  storage::ConcurrentIdMapper<storage::Label> &label_mapper() override;
-  storage::ConcurrentIdMapper<storage::EdgeType> &edge_type_mapper() override;
-  storage::ConcurrentIdMapper<storage::Property> &property_mapper() override;
-  database::Counters &counters() override;
-  void CollectGarbage() override;
-
-  bool MakeSnapshot(GraphDbAccessor &accessor) override;
-  void ReinitializeStorage() override;
-
- private:
-  std::unique_ptr<impl::SingleNode> impl_;
 
   std::unique_ptr<utils::Scheduler> snapshot_creator_;
   utils::Scheduler transaction_killer_;
-};
 
-class SingleNodeRecoveryTransanctions final
-    : public durability::RecoveryTransactions {
- public:
-  explicit SingleNodeRecoveryTransanctions(SingleNode *db);
-  ~SingleNodeRecoveryTransanctions();
+  Config config_;
+  std::unique_ptr<Storage> storage_ =
+      std::make_unique<Storage>(config_.worker_id, config_.properties_on_disk);
+  durability::WriteAheadLog wal_{
+      config_.worker_id, config_.durability_directory,
+      config_.durability_enabled, config_.synchronous_commit};
 
-  void Begin(const tx::TransactionId &tx_id) override;
-  void Abort(const tx::TransactionId &tx_id) override;
-  void Commit(const tx::TransactionId &tx_id) override;
-  void Apply(const database::StateDelta &delta) override;
-
- private:
-  SingleNode *db_;
-  std::unordered_map<tx::TransactionId, std::unique_ptr<GraphDbAccessor>>
-      accessors_;
+  tx::Engine tx_engine_{&wal_};
+  std::unique_ptr<StorageGc> storage_gc_ =
+      std::make_unique<StorageGc>(*storage_, tx_engine_, config_.gc_cycle_sec);
+  storage::ConcurrentIdMapper<storage::Label> label_mapper_{
+      storage_->PropertiesOnDisk()};
+  storage::ConcurrentIdMapper<storage::EdgeType> edge_mapper_{
+      storage_->PropertiesOnDisk()};
+  storage::ConcurrentIdMapper<storage::Property> property_mapper_{
+      storage_->PropertiesOnDisk()};
+  database::Counters counters_;
 };
 
 }  // namespace database
diff --git a/src/database/single_node/graph_db_accessor.hpp b/src/database/single_node/graph_db_accessor.hpp
index e0f98a978..cf7d90b2b 100644
--- a/src/database/single_node/graph_db_accessor.hpp
+++ b/src/database/single_node/graph_db_accessor.hpp
@@ -45,6 +45,7 @@ class GraphDbAccessor {
   // the code.
   friend class ::RecordAccessor<Vertex>;
   friend class ::VertexAccessor;
+  friend class GraphDb;
 
  protected:
   // Construction should only be done through GraphDb::Access function and
@@ -56,16 +57,13 @@ class GraphDbAccessor {
   GraphDbAccessor(GraphDb &db, tx::TransactionId tx_id);
 
  public:
-  virtual ~GraphDbAccessor();
+  ~GraphDbAccessor();
 
   GraphDbAccessor(const GraphDbAccessor &other) = delete;
   GraphDbAccessor(GraphDbAccessor &&other) = delete;
   GraphDbAccessor &operator=(const GraphDbAccessor &other) = delete;
   GraphDbAccessor &operator=(GraphDbAccessor &&other) = delete;
 
-  virtual ::VertexAccessor::Impl *GetVertexImpl() = 0;
-  virtual ::RecordAccessor<Edge>::Impl *GetEdgeImpl() = 0;
-
   /**
    * Creates a new Vertex and returns an accessor to it. If the ID is
    * provided, the created Vertex will have that local ID, and the ID counter
@@ -101,8 +99,7 @@ class GraphDbAccessor {
    * before deletion.
    * @return  If or not the vertex was deleted.
    */
-  virtual bool RemoveVertex(VertexAccessor &vertex_accessor,
-                            bool check_empty = true);
+  bool RemoveVertex(VertexAccessor &vertex_accessor, bool check_empty = true);
 
   /**
    * Removes the vertex of the given accessor along with all it's outgoing
@@ -340,8 +337,8 @@ class GraphDbAccessor {
    * @param remove_in_edge If the edge should be removed from the its
    * destination side.
    */
-  virtual void RemoveEdge(EdgeAccessor &edge, bool remove_out_edge = true,
-                          bool remove_in_edge = true);
+  void RemoveEdge(EdgeAccessor &edge, bool remove_out_edge = true,
+                  bool remove_in_edge = true);
 
   /**
    * Obtains the edge for the given ID. If there is no edge for the given
@@ -444,7 +441,7 @@ class GraphDbAccessor {
    * @param label - label to build for
    * @param property - property to build for
    */
-  virtual void BuildIndex(storage::Label label, storage::Property property);
+  void BuildIndex(storage::Label label, storage::Property property);
 
   /// Populates index with vertices containing the key
   void PopulateIndex(const LabelPropertyIndex::Key &key);
@@ -574,7 +571,7 @@ class GraphDbAccessor {
   tx::TransactionId transaction_id() const;
 
   /** Advances transaction's command id by 1. */
-  virtual void AdvanceCommand();
+  void AdvanceCommand();
 
   /** Commit transaction. */
   void Commit();
@@ -621,10 +618,10 @@ class GraphDbAccessor {
 
  protected:
   /** Called in `BuildIndex` after creating an index, but before populating. */
-  virtual void PostCreateIndex(const LabelPropertyIndex::Key &key) {}
+  void PostCreateIndex(const LabelPropertyIndex::Key &key) {}
 
   /** Populates the index from a *new* transaction after creating the index. */
-  virtual void PopulateIndexFromBuildIndex(const LabelPropertyIndex::Key &key) {
+  void PopulateIndexFromBuildIndex(const LabelPropertyIndex::Key &key) {
     PopulateIndex(key);
   }
 
@@ -632,7 +629,7 @@ class GraphDbAccessor {
    * Insert a new edge to `from` vertex and return the address.
    * Called from `InsertEdge` as the first step in edge insertion.
    * */
-  virtual storage::EdgeAddress InsertEdgeOnFrom(
+  storage::EdgeAddress InsertEdgeOnFrom(
       VertexAccessor *from, VertexAccessor *to,
       const storage::EdgeType &edge_type,
       const std::experimental::optional<gid::Gid> &requested_gid,
@@ -643,9 +640,9 @@ class GraphDbAccessor {
    * Called after `InsertEdgeOnFrom` in `InsertEdge`. The given `edge_address`
    * is from the created edge, returned by `InsertEdgeOnFrom`.
    */
-  virtual void InsertEdgeOnTo(VertexAccessor *from, VertexAccessor *to,
-                              const storage::EdgeType &edge_type,
-                              const storage::EdgeAddress &edge_address);
+  void InsertEdgeOnTo(VertexAccessor *from, VertexAccessor *to,
+                      const storage::EdgeType &edge_type,
+                      const storage::EdgeAddress &edge_address);
 
  private:
   GraphDb &db_;
diff --git a/src/durability/single_node/recovery.cpp b/src/durability/single_node/recovery.cpp
index 55d024326..1f95a8127 100644
--- a/src/durability/single_node/recovery.cpp
+++ b/src/durability/single_node/recovery.cpp
@@ -419,6 +419,36 @@ RecoveryInfo RecoverOnlySnapshot(
                                          *recovery_data)};
 }
 
+RecoveryTransactions::RecoveryTransactions(database::GraphDb *db) : db_(db) {}
+
+void RecoveryTransactions::Begin(const tx::TransactionId &tx_id) {
+  CHECK(accessors_.find(tx_id) == accessors_.end())
+      << "Double transaction start";
+  accessors_.emplace(tx_id, db_->Access());
+}
+
+void RecoveryTransactions::Abort(const tx::TransactionId &tx_id) {
+  GetAccessor(tx_id)->Abort();
+  accessors_.erase(accessors_.find(tx_id));
+}
+
+void RecoveryTransactions::Commit(const tx::TransactionId &tx_id) {
+  GetAccessor(tx_id)->Commit();
+  accessors_.erase(accessors_.find(tx_id));
+}
+
+void RecoveryTransactions::Apply(const database::StateDelta &delta) {
+  delta.Apply(*GetAccessor(delta.transaction_id));
+}
+
+database::GraphDbAccessor *RecoveryTransactions::GetAccessor(
+    const tx::TransactionId &tx_id) {
+  auto found = accessors_.find(tx_id);
+  CHECK(found != accessors_.end())
+      << "Accessor does not exist for transaction: " << tx_id;
+  return found->second.get();
+}
+
 // TODO - finer-grained recovery feedback could be useful here.
 void RecoverWal(const fs::path &durability_dir, database::GraphDb *db,
                 RecoveryData *recovery_data,
diff --git a/src/durability/single_node/recovery.hpp b/src/durability/single_node/recovery.hpp
index 60c320ceb..93d26c350 100644
--- a/src/durability/single_node/recovery.hpp
+++ b/src/durability/single_node/recovery.hpp
@@ -116,12 +116,23 @@ RecoveryInfo RecoverOnlySnapshot(
 /** Interface for accessing transactions during WAL recovery. */
 class RecoveryTransactions {
  public:
-  virtual ~RecoveryTransactions() {}
+  RecoveryTransactions(database::GraphDb *db);
 
-  virtual void Begin(const tx::TransactionId &) = 0;
-  virtual void Abort(const tx::TransactionId &) = 0;
-  virtual void Commit(const tx::TransactionId &) = 0;
-  virtual void Apply(const database::StateDelta &) = 0;
+  void Begin(const tx::TransactionId &tx_id);
+
+  void Abort(const tx::TransactionId &tx_id);
+
+  void Commit(const tx::TransactionId &tx_id);
+
+  void Apply(const database::StateDelta &delta);
+
+ private:
+  database::GraphDbAccessor *GetAccessor(const tx::TransactionId &tx_id);
+
+  database::GraphDb *db_;
+  std::unordered_map<tx::TransactionId,
+                     std::unique_ptr<database::GraphDbAccessor>>
+      accessors_;
 };
 
 void RecoverWal(const std::experimental::filesystem::path &durability_dir,
diff --git a/src/memgraph.cpp b/src/memgraph.cpp
index 7f357e92a..24a49314a 100644
--- a/src/memgraph.cpp
+++ b/src/memgraph.cpp
@@ -44,7 +44,7 @@ using communication::ServerContext;
 
 void SingleNodeMain() {
   google::SetUsageMessage("Memgraph single-node database server");
-  database::SingleNode db;
+  database::GraphDb db;
   query::Interpreter interpreter;
   SessionData session_data{&db, &interpreter};
 
diff --git a/src/mvcc/distributed/record.hpp b/src/mvcc/distributed/record.hpp
index 1f69a0e9d..6de7c93ad 100644
--- a/src/mvcc/distributed/record.hpp
+++ b/src/mvcc/distributed/record.hpp
@@ -5,7 +5,7 @@
 #include <iostream>
 
 #include "transactions/commit_log.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 #include "transactions/transaction.hpp"
 
 #include "mvcc/common/version.hpp"
diff --git a/src/mvcc/single_node/record.hpp b/src/mvcc/single_node/record.hpp
index 1f69a0e9d..022c1a6e8 100644
--- a/src/mvcc/single_node/record.hpp
+++ b/src/mvcc/single_node/record.hpp
@@ -5,7 +5,7 @@
 #include <iostream>
 
 #include "transactions/commit_log.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "transactions/transaction.hpp"
 
 #include "mvcc/common/version.hpp"
diff --git a/src/storage/common/concurrent_id_mapper.hpp b/src/storage/distributed/concurrent_id_mapper.hpp
similarity index 100%
rename from src/storage/common/concurrent_id_mapper.hpp
rename to src/storage/distributed/concurrent_id_mapper.hpp
diff --git a/src/storage/distributed/concurrent_id_mapper_single_node.hpp b/src/storage/distributed/concurrent_id_mapper_single_node.hpp
index b84d773c9..834e66532 100644
--- a/src/storage/distributed/concurrent_id_mapper_single_node.hpp
+++ b/src/storage/distributed/concurrent_id_mapper_single_node.hpp
@@ -3,8 +3,8 @@
 #include <mutex>
 
 #include "data_structures/concurrent/concurrent_map.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
 #include "storage/common/types.hpp"
+#include "storage/distributed/concurrent_id_mapper.hpp"
 #include "utils/algorithm.hpp"
 
 namespace storage {
diff --git a/src/storage/distributed/concurrent_id_mapper_worker.hpp b/src/storage/distributed/concurrent_id_mapper_worker.hpp
index 87f25bb47..11e4dc24f 100644
--- a/src/storage/distributed/concurrent_id_mapper_worker.hpp
+++ b/src/storage/distributed/concurrent_id_mapper_worker.hpp
@@ -3,7 +3,7 @@
 #include "communication/rpc/client_pool.hpp"
 #include "data_structures/concurrent/concurrent_map.hpp"
 #include "io/network/endpoint.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
+#include "storage/distributed/concurrent_id_mapper.hpp"
 
 namespace storage {
 
diff --git a/src/storage/distributed/garbage_collector.hpp b/src/storage/distributed/garbage_collector.hpp
index f0e1c0375..9b60b7db1 100644
--- a/src/storage/distributed/garbage_collector.hpp
+++ b/src/storage/distributed/garbage_collector.hpp
@@ -5,7 +5,7 @@
 #include "data_structures/concurrent/skiplist.hpp"
 #include "mvcc/distributed/version_list.hpp"
 #include "storage/distributed/deferred_deleter.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 
 /**
  * @brief - Garbage collects deleted records.
diff --git a/src/storage/distributed/storage_gc.hpp b/src/storage/distributed/storage_gc.hpp
index 304c68ad3..700abe090 100644
--- a/src/storage/distributed/storage_gc.hpp
+++ b/src/storage/distributed/storage_gc.hpp
@@ -12,7 +12,7 @@
 #include "storage/distributed/gid.hpp"
 #include "storage/distributed/storage.hpp"
 #include "storage/distributed/vertex.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 #include "utils/exceptions.hpp"
 #include "utils/scheduler.hpp"
 #include "utils/timer.hpp"
diff --git a/src/storage/single_node/concurrent_id_mapper_single_node.hpp b/src/storage/single_node/concurrent_id_mapper.hpp
similarity index 86%
rename from src/storage/single_node/concurrent_id_mapper_single_node.hpp
rename to src/storage/single_node/concurrent_id_mapper.hpp
index b84d773c9..745bca682 100644
--- a/src/storage/single_node/concurrent_id_mapper_single_node.hpp
+++ b/src/storage/single_node/concurrent_id_mapper.hpp
@@ -3,7 +3,6 @@
 #include <mutex>
 
 #include "data_structures/concurrent/concurrent_map.hpp"
-#include "storage/common/concurrent_id_mapper.hpp"
 #include "storage/common/types.hpp"
 #include "utils/algorithm.hpp"
 
@@ -11,16 +10,16 @@ namespace storage {
 
 /** SingleNode implementation of ConcurrentIdMapper. */
 template <typename TId>
-class SingleNodeConcurrentIdMapper : public ConcurrentIdMapper<TId> {
+class ConcurrentIdMapper {
   using StorageT = typename TId::IdT;
 
  public:
-  SingleNodeConcurrentIdMapper() = default;
-  explicit SingleNodeConcurrentIdMapper(
+  ConcurrentIdMapper() = default;
+  explicit ConcurrentIdMapper(
       const std::vector<std::string> &properties_on_disk)
       : properties_on_disk_(properties_on_disk) {}
 
-  TId value_to_id(const std::string &value) override {
+  TId value_to_id(const std::string &value) {
     auto value_to_id_acc = value_to_id_.access();
     auto found = value_to_id_acc.find(value);
     TId inserted_id(0);
@@ -46,7 +45,7 @@ class SingleNodeConcurrentIdMapper : public ConcurrentIdMapper<TId> {
     return inserted_id;
   }
 
-  const std::string &id_to_value(const TId &id) override {
+  const std::string &id_to_value(const TId &id) {
     auto id_to_value_acc = id_to_value_.access();
     auto result = id_to_value_acc.find(id);
     DCHECK(result != id_to_value_acc.end());
diff --git a/src/storage/single_node/edge_accessor.cpp b/src/storage/single_node/edge_accessor.cpp
index 1daccfb42..a12fad91a 100644
--- a/src/storage/single_node/edge_accessor.cpp
+++ b/src/storage/single_node/edge_accessor.cpp
@@ -6,7 +6,7 @@
 
 EdgeAccessor::EdgeAccessor(EdgeAddress address,
                            database::GraphDbAccessor &db_accessor)
-    : RecordAccessor(address, db_accessor, db_accessor.GetEdgeImpl()),
+    : RecordAccessor(address, db_accessor),
       from_(nullptr),
       to_(nullptr),
       edge_type_() {
@@ -22,7 +22,7 @@ EdgeAccessor::EdgeAccessor(EdgeAddress address,
                            database::GraphDbAccessor &db_accessor,
                            VertexAddress from, VertexAddress to,
                            storage::EdgeType edge_type)
-    : RecordAccessor(address, db_accessor, db_accessor.GetEdgeImpl()),
+    : RecordAccessor(address, db_accessor),
       from_(from),
       to_(to),
       edge_type_(edge_type) {}
diff --git a/src/storage/single_node/garbage_collector.hpp b/src/storage/single_node/garbage_collector.hpp
index a6581d00e..40230c3e7 100644
--- a/src/storage/single_node/garbage_collector.hpp
+++ b/src/storage/single_node/garbage_collector.hpp
@@ -5,7 +5,7 @@
 #include "data_structures/concurrent/skiplist.hpp"
 #include "mvcc/single_node/version_list.hpp"
 #include "storage/single_node/deferred_deleter.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/single_node/engine.hpp"
 
 /**
  * @brief - Garbage collects deleted records.
diff --git a/src/storage/single_node/record_accessor.cpp b/src/storage/single_node/record_accessor.cpp
index 443f38ec2..d9dc580d8 100644
--- a/src/storage/single_node/record_accessor.cpp
+++ b/src/storage/single_node/record_accessor.cpp
@@ -11,10 +11,8 @@ using database::StateDelta;
 
 template <typename TRecord>
 RecordAccessor<TRecord>::RecordAccessor(AddressT address,
-                                        database::GraphDbAccessor &db_accessor,
-                                        Impl *impl)
-    : impl_(impl),
-      db_accessor_(&db_accessor),
+                                        database::GraphDbAccessor &db_accessor)
+    : db_accessor_(&db_accessor),
       address_(db_accessor.db().storage().LocalizedAddressIfPossible(address)) {
 }
 
@@ -107,7 +105,10 @@ typename RecordAccessor<TRecord>::AddressT RecordAccessor<TRecord>::address()
 template <typename TRecord>
 typename RecordAccessor<TRecord>::AddressT
 RecordAccessor<TRecord>::GlobalAddress() const {
-  return impl_->GlobalAddress(*this);
+  // TODO: This is still coupled to distributed storage, albeit loosely.
+  int worker_id = 0;
+  CHECK(is_local());
+  return storage::Address<mvcc::VersionList<TRecord>>(gid(), worker_id);
 }
 
 template <typename TRecord>
@@ -138,7 +139,10 @@ RecordAccessor<TRecord> &RecordAccessor<TRecord>::SwitchOld() {
 
 template <typename TRecord>
 bool RecordAccessor<TRecord>::Reconstruct() const {
-  impl_->SetOldNew(*this, &old_, &new_);
+  auto &dba = db_accessor();
+  const auto &addr = address();
+  CHECK(is_local());
+  addr.local()->find_set_old_new(dba.transaction(), &old_, &new_);
   current_ = old_ ? old_ : new_;
   return old_ != nullptr || new_ != nullptr;
 }
@@ -160,14 +164,17 @@ TRecord &RecordAccessor<TRecord>::update() const {
 
   if (new_) return *new_;
 
-  new_ = impl_->FindNew(*this);
+  const auto &addr = address();
+  CHECK(addr.is_local());
+  new_ = addr.local()->update(dba.transaction());
+
   DCHECK(new_ != nullptr) << "RecordAccessor.new_ is null after update";
   return *new_;
 }
 
 template <typename TRecord>
 int64_t RecordAccessor<TRecord>::CypherId() const {
-  return impl_->CypherId(*this);
+  return address().local()->cypher_id();
 }
 
 template <typename TRecord>
@@ -184,7 +191,8 @@ const TRecord &RecordAccessor<TRecord>::current() const {
 template <typename TRecord>
 void RecordAccessor<TRecord>::ProcessDelta(
     const database::StateDelta &delta) const {
-  impl_->ProcessDelta(*this, delta);
+  CHECK(is_local());
+  db_accessor().wal().Emplace(delta);
 }
 
 template class RecordAccessor<Vertex>;
diff --git a/src/storage/single_node/record_accessor.hpp b/src/storage/single_node/record_accessor.hpp
index a32a15446..df2a7ea76 100644
--- a/src/storage/single_node/record_accessor.hpp
+++ b/src/storage/single_node/record_accessor.hpp
@@ -27,34 +27,27 @@ struct StateDelta;
  */
 template <typename TRecord>
 class RecordAccessor : public utils::TotalOrdering<RecordAccessor<TRecord>> {
- public:
+ protected:
   using AddressT = storage::Address<mvcc::VersionList<TRecord>>;
 
   /**
-   * Interface for the underlying implementation of the record accessor.
-   * The RecordAccessor only borrows the pointer to the implementation, it does
-   * *not* own it. When a RecordAccessor is copied, so is the pointer but *not*
-   * the implementation itself. This means that concrete Impl types need to be
-   * shareable among different accessors. To achieve that, it's best for derived
-   * Impl types to contain *no state*. The reason we are using this approach is
-   * to prevent large amounts of allocations, because RecordAccessor are often
-   * created and copied.
+   * The database::GraphDbAccessor is friend to this accessor so it can
+   * operate on it's data (mvcc version-list and the record itself).
+   * This is legitimate because database::GraphDbAccessor creates
+   * RecordAccessors
+   * and is semantically their parent/owner. It is necessary because
+   * the database::GraphDbAccessor handles insertions and deletions, and these
+   * operations modify data intensively.
    */
-  class Impl {
-   public:
-    virtual ~Impl() {}
+  friend database::GraphDbAccessor;
 
-    virtual AddressT GlobalAddress(const RecordAccessor<TRecord> &ra) = 0;
-    /** Set the pointers for old and new records during `Reconstruct`. */
-    virtual void SetOldNew(const RecordAccessor<TRecord> &ra,
-                           TRecord **old_record, TRecord **new_record) = 0;
-    /** Find the pointer to the new, updated record. */
-    virtual TRecord *FindNew(const RecordAccessor<TRecord> &ra) = 0;
-    /** Process a change delta, e.g. by writing WAL. */
-    virtual void ProcessDelta(const RecordAccessor<TRecord> &ra,
-                              const database::StateDelta &delta) = 0;
-    virtual int64_t CypherId(const RecordAccessor<TRecord> &ra) = 0;
-  };
+ public:
+  /**
+   * @param address Address (local or global) of the Vertex/Edge of this
+   * accessor.
+   * @param db_accessor The DB accessor that "owns" this record accessor.
+   */
+  RecordAccessor(AddressT address, database::GraphDbAccessor &db_accessor);
 
   // this class is default copyable, movable and assignable
   RecordAccessor(const RecordAccessor &other) = default;
@@ -62,25 +55,6 @@ class RecordAccessor : public utils::TotalOrdering<RecordAccessor<TRecord>> {
   RecordAccessor &operator=(const RecordAccessor &other) = default;
   RecordAccessor &operator=(RecordAccessor &&other) = default;
 
- protected:
-  /**
-   * Protected destructor because we allow inheritance, but nobody should own a
-   * pointer to plain RecordAccessor.
-   */
-  ~RecordAccessor() = default;
-
-  /**
-   * Only derived types may allow construction.
-   *
-   * @param address Address (local or global) of the Vertex/Edge of this
-   * accessor.
-   * @param db_accessor The DB accessor that "owns" this record accessor.
-   * @param impl Borrowed pointer to the underlying implementation.
-   */
-  RecordAccessor(AddressT address, database::GraphDbAccessor &db_accessor,
-                 Impl *impl);
-
- public:
   /** Gets the property for the given key. */
   PropertyValue PropsAt(storage::Property key) const;
 
@@ -183,17 +157,6 @@ class RecordAccessor : public utils::TotalOrdering<RecordAccessor<TRecord>> {
   int64_t CypherId() const;
 
  protected:
-  /**
-   * The database::GraphDbAccessor is friend to this accessor so it can
-   * operate on it's data (mvcc version-list and the record itself).
-   * This is legitimate because database::GraphDbAccessor creates
-   * RecordAccessors
-   * and is semantically their parent/owner. It is necessary because
-   * the database::GraphDbAccessor handles insertions and deletions, and these
-   * operations modify data intensively.
-   */
-  friend database::GraphDbAccessor;
-
   /** Process a change delta, e.g. by writing WAL. */
   void ProcessDelta(const database::StateDelta &delta) const;
 
@@ -212,7 +175,6 @@ class RecordAccessor : public utils::TotalOrdering<RecordAccessor<TRecord>> {
   const TRecord &current() const;
 
  private:
-  Impl *impl_;
   // The database accessor for which this record accessor is created
   // Provides means of getting to the transaction and database functions.
   // Immutable, set in the constructor and never changed.
diff --git a/src/storage/single_node/storage_gc.hpp b/src/storage/single_node/storage_gc.hpp
index c068c896d..e9fb7317e 100644
--- a/src/storage/single_node/storage_gc.hpp
+++ b/src/storage/single_node/storage_gc.hpp
@@ -12,7 +12,7 @@
 #include "storage/single_node/gid.hpp"
 #include "storage/single_node/storage.hpp"
 #include "storage/single_node/vertex.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "utils/exceptions.hpp"
 #include "utils/scheduler.hpp"
 #include "utils/timer.hpp"
@@ -59,7 +59,10 @@ class StorageGc {
           });
   }
 
-  virtual ~StorageGc() {
+  ~StorageGc() {
+    // We have to stop the scheduler before destroying this class.
+    scheduler_.Stop();
+
     edges_.record_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
     vertices_.record_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
     edges_.version_list_deleter_.FreeExpiredObjects(tx::Transaction::MaxId());
@@ -72,7 +75,10 @@ class StorageGc {
   StorageGc &operator=(const StorageGc &) = delete;
   StorageGc &operator=(StorageGc &&) = delete;
 
-  virtual void CollectCommitLogGarbage(tx::TransactionId oldest_active) = 0;
+  void CollectCommitLogGarbage(tx::TransactionId oldest_active) {
+    auto safe_to_delete = GetClogSafeTransaction(oldest_active);
+    if (safe_to_delete) tx_engine_.GarbageCollectCommitLog(*safe_to_delete);
+  }
 
   void CollectGarbage() {
     // main garbage collection logic
diff --git a/src/storage/single_node/storage_gc_single_node.hpp b/src/storage/single_node/storage_gc_single_node.hpp
deleted file mode 100644
index cfa7b8f8b..000000000
--- a/src/storage/single_node/storage_gc_single_node.hpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#pragma once
-
-#include "storage/single_node/storage_gc.hpp"
-
-namespace database {
-class StorageGcSingleNode : public StorageGc {
- public:
-  using StorageGc::StorageGc;
-
-  ~StorageGcSingleNode() {
-    // We have to stop scheduler before destroying this class because otherwise
-    // a task might try to utilize methods in this class which might cause pure
-    // virtual method called since they are not implemented for the base class.
-    scheduler_.Stop();
-  }
-
-  void CollectCommitLogGarbage(tx::TransactionId oldest_active) final {
-    auto safe_to_delete = GetClogSafeTransaction(oldest_active);
-    if (safe_to_delete) tx_engine_.GarbageCollectCommitLog(*safe_to_delete);
-  }
-};
-}  // namespace database
diff --git a/src/storage/single_node/vertex_accessor.cpp b/src/storage/single_node/vertex_accessor.cpp
index 3f5631d88..f350bb75a 100644
--- a/src/storage/single_node/vertex_accessor.cpp
+++ b/src/storage/single_node/vertex_accessor.cpp
@@ -8,8 +8,7 @@
 
 VertexAccessor::VertexAccessor(VertexAddress address,
                                database::GraphDbAccessor &db_accessor)
-    : RecordAccessor(address, db_accessor, db_accessor.GetVertexImpl()),
-      impl_(db_accessor.GetVertexImpl()) {
+    : RecordAccessor(address, db_accessor) {
   Reconstruct();
 }
 
@@ -18,11 +17,32 @@ size_t VertexAccessor::out_degree() const { return current().out_.size(); }
 size_t VertexAccessor::in_degree() const { return current().in_.size(); }
 
 void VertexAccessor::add_label(storage::Label label) {
-  return impl_->AddLabel(*this, label);
+  CHECK(is_local());
+  auto &dba = db_accessor();
+  auto delta = database::StateDelta::AddLabel(dba.transaction_id(), gid(),
+                                              label, dba.LabelName(label));
+  Vertex &vertex = update();
+  // not a duplicate label, add it
+  if (!utils::Contains(vertex.labels_, label)) {
+    vertex.labels_.emplace_back(label);
+    dba.wal().Emplace(delta);
+    dba.UpdateLabelIndices(label, *this, &vertex);
+  }
 }
 
 void VertexAccessor::remove_label(storage::Label label) {
-  return impl_->RemoveLabel(*this, label);
+  CHECK(is_local());
+  auto &dba = db_accessor();
+  auto delta = database::StateDelta::RemoveLabel(dba.transaction_id(), gid(),
+                                                 label, dba.LabelName(label));
+  Vertex &vertex = update();
+  if (utils::Contains(vertex.labels_, label)) {
+    auto &labels = vertex.labels_;
+    auto found = std::find(labels.begin(), labels.end(), delta.label);
+    std::swap(*found, labels.back());
+    labels.pop_back();
+    dba.wal().Emplace(delta);
+  }
 }
 
 bool VertexAccessor::has_label(storage::Label label) const {
diff --git a/src/storage/single_node/vertex_accessor.hpp b/src/storage/single_node/vertex_accessor.hpp
index 4b9486bd1..6efeefc00 100644
--- a/src/storage/single_node/vertex_accessor.hpp
+++ b/src/storage/single_node/vertex_accessor.hpp
@@ -49,15 +49,6 @@ class VertexAccessor final : public RecordAccessor<Vertex> {
   }
 
  public:
-  /** Like RecordAccessor::Impl with addition of Vertex specific methods. */
-  class Impl : public RecordAccessor<Vertex>::Impl {
-   public:
-    virtual void AddLabel(const VertexAccessor &va,
-                          const storage::Label &label) = 0;
-    virtual void RemoveLabel(const VertexAccessor &va,
-                             const storage::Label &label) = 0;
-  };
-
   VertexAccessor(VertexAddress address, database::GraphDbAccessor &db_accessor);
 
   /** Returns the number of outgoing edges. */
@@ -153,9 +144,6 @@ class VertexAccessor final : public RecordAccessor<Vertex> {
    * this operation should always be accompanied by the removal of the edge from
    * the outgoing edges on the other side and edge deletion. */
   void RemoveInEdge(storage::EdgeAddress edge);
-
- private:
-  Impl *impl_{nullptr};
 };
 
 std::ostream &operator<<(std::ostream &, const VertexAccessor &);
diff --git a/src/transactions/distributed/engine.hpp b/src/transactions/distributed/engine.hpp
new file mode 100644
index 000000000..153b164ef
--- /dev/null
+++ b/src/transactions/distributed/engine.hpp
@@ -0,0 +1,111 @@
+/// @file
+
+#pragma once
+
+#include <algorithm>
+#include <mutex>
+#include <vector>
+
+#include "data_structures/concurrent/concurrent_map.hpp"
+#include "transactions/commit_log.hpp"
+#include "transactions/snapshot.hpp"
+#include "transactions/transaction.hpp"
+#include "transactions/type.hpp"
+
+namespace tx {
+/// Database transaction engine. Used for managing transactions and the related
+/// information such as transaction snapshots and the transaction state info.
+///
+/// This is an abstract base class for implementing a transactional engine.
+///
+/// Methods in this class are often prefixed with "Global" or "Local", depending
+/// on the guarantees that they need to satisfy. These guarantee requirements
+/// are determined by the users of a particular method.
+class Engine {
+ public:
+  virtual ~Engine() = default;
+
+  /// Begins a transaction and returns a pointer to it's object.
+  virtual Transaction *Begin() = 0;
+
+  /// Advances the command on the transaction with the given id.
+  virtual CommandId Advance(TransactionId id) = 0;
+
+  /// Updates the command on the workers to the master's value.
+  virtual CommandId UpdateCommand(TransactionId id) = 0;
+
+  /// Comits the given transaction. Deletes the transaction object, it's not
+  /// valid after this function executes.
+  virtual void Commit(const Transaction &t) = 0;
+
+  /// Aborts the given transaction. Deletes the transaction object, it's not
+  /// valid after this function executes.
+  virtual void Abort(const Transaction &t) = 0;
+
+  /// Returns the commit log Info about the given transaction.
+  virtual CommitLog::Info Info(TransactionId tx) const = 0;
+
+  /// Returns the snapshot relevant to garbage collection of database records.
+  ///
+  /// If there are no active transactions that means a snapshot containing only
+  /// the next transaction ID.  If there are active transactions, that means the
+  /// oldest active transaction's snapshot, with that transaction's ID appened
+  /// as last.
+  ///
+  /// The idea is that data records can only be deleted if they were expired
+  /// (and that was committed) by a transaction older than the older currently
+  /// active. We need the full snapshot to prevent overlaps (see general GC
+  /// documentation).
+  ///
+  /// The returned snapshot must be for the globally oldest active transaction.
+  /// If we only looked at locally known transactions, it would be possible to
+  /// delete something that and older active transaction can still see.
+  virtual Snapshot GlobalGcSnapshot() = 0;
+
+  /// Returns active transactions.
+  virtual Snapshot GlobalActiveTransactions() = 0;
+
+  /// Returns the ID the last globally known transaction.
+  virtual tx::TransactionId GlobalLast() const = 0;
+
+  /// Returns the ID of last locally known transaction.
+  virtual tx::TransactionId LocalLast() const = 0;
+
+  /// Returns the ID of the oldest transaction locally known to be active. It is
+  /// guaranteed that all the transactions older than the returned are globally
+  /// not active.
+  virtual TransactionId LocalOldestActive() const = 0;
+
+  /// Calls function f on each locally active transaction.
+  virtual void LocalForEachActiveTransaction(
+      std::function<void(Transaction &)> f) = 0;
+
+  /// Gets a transaction object for a running transaction.
+  virtual tx::Transaction *RunningTransaction(TransactionId tx_id) = 0;
+
+  /// Ensures the next transaction that starts will have the ID greater than
+  /// the given id.
+  virtual void EnsureNextIdGreater(TransactionId tx_id) = 0;
+
+  /// Garbage collects transactions older than tx_id from commit log.
+  virtual void GarbageCollectCommitLog(TransactionId tx_id) = 0;
+
+  auto &local_lock_graph() { return local_lock_graph_; }
+  const auto &local_lock_graph() const { return local_lock_graph_; }
+
+ protected:
+  Transaction *CreateTransaction(TransactionId id, const Snapshot &snapshot) {
+    return new Transaction(id, snapshot, *this);
+  }
+
+  CommandId AdvanceCommand(Transaction *t) { return t->AdvanceCommand(); }
+
+  void SetCommand(Transaction *t, CommandId cid) { t->SetCommand(cid); }
+
+ private:
+  // Map lock dependencies. Each entry maps (tx_that_wants_lock,
+  // tx_that_holds_lock). Used for local deadlock resolution.
+  // TODO consider global deadlock resolution.
+  ConcurrentMap<TransactionId, TransactionId> local_lock_graph_;
+};
+}  // namespace tx
diff --git a/src/transactions/distributed/engine_distributed.hpp b/src/transactions/distributed/engine_distributed.hpp
index 021580931..c3a70c3a9 100644
--- a/src/transactions/distributed/engine_distributed.hpp
+++ b/src/transactions/distributed/engine_distributed.hpp
@@ -4,7 +4,7 @@
 
 #include "communication/rpc/server.hpp"
 #include "distributed/coordination.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 #include "utils/exceptions.hpp"
 
 namespace tx {
diff --git a/src/transactions/distributed/engine_single_node.hpp b/src/transactions/distributed/engine_single_node.hpp
index d93651211..718855f9f 100644
--- a/src/transactions/distributed/engine_single_node.hpp
+++ b/src/transactions/distributed/engine_single_node.hpp
@@ -8,7 +8,7 @@
 
 #include "durability/distributed/wal.hpp"
 #include "transactions/commit_log.hpp"
-#include "transactions/engine.hpp"
+#include "transactions/distributed/engine.hpp"
 #include "transactions/transaction.hpp"
 #include "utils/thread/sync.hpp"
 
diff --git a/src/transactions/engine.hpp b/src/transactions/engine.hpp
index 153b164ef..aa9b30667 100644
--- a/src/transactions/engine.hpp
+++ b/src/transactions/engine.hpp
@@ -1,111 +1,9 @@
-/// @file
-
 #pragma once
 
-#include <algorithm>
-#include <mutex>
-#include <vector>
+#ifdef MG_SINGLE_NODE
+#include "transactions/single_node/engine.hpp"
+#endif
 
-#include "data_structures/concurrent/concurrent_map.hpp"
-#include "transactions/commit_log.hpp"
-#include "transactions/snapshot.hpp"
-#include "transactions/transaction.hpp"
-#include "transactions/type.hpp"
-
-namespace tx {
-/// Database transaction engine. Used for managing transactions and the related
-/// information such as transaction snapshots and the transaction state info.
-///
-/// This is an abstract base class for implementing a transactional engine.
-///
-/// Methods in this class are often prefixed with "Global" or "Local", depending
-/// on the guarantees that they need to satisfy. These guarantee requirements
-/// are determined by the users of a particular method.
-class Engine {
- public:
-  virtual ~Engine() = default;
-
-  /// Begins a transaction and returns a pointer to it's object.
-  virtual Transaction *Begin() = 0;
-
-  /// Advances the command on the transaction with the given id.
-  virtual CommandId Advance(TransactionId id) = 0;
-
-  /// Updates the command on the workers to the master's value.
-  virtual CommandId UpdateCommand(TransactionId id) = 0;
-
-  /// Comits the given transaction. Deletes the transaction object, it's not
-  /// valid after this function executes.
-  virtual void Commit(const Transaction &t) = 0;
-
-  /// Aborts the given transaction. Deletes the transaction object, it's not
-  /// valid after this function executes.
-  virtual void Abort(const Transaction &t) = 0;
-
-  /// Returns the commit log Info about the given transaction.
-  virtual CommitLog::Info Info(TransactionId tx) const = 0;
-
-  /// Returns the snapshot relevant to garbage collection of database records.
-  ///
-  /// If there are no active transactions that means a snapshot containing only
-  /// the next transaction ID.  If there are active transactions, that means the
-  /// oldest active transaction's snapshot, with that transaction's ID appened
-  /// as last.
-  ///
-  /// The idea is that data records can only be deleted if they were expired
-  /// (and that was committed) by a transaction older than the older currently
-  /// active. We need the full snapshot to prevent overlaps (see general GC
-  /// documentation).
-  ///
-  /// The returned snapshot must be for the globally oldest active transaction.
-  /// If we only looked at locally known transactions, it would be possible to
-  /// delete something that and older active transaction can still see.
-  virtual Snapshot GlobalGcSnapshot() = 0;
-
-  /// Returns active transactions.
-  virtual Snapshot GlobalActiveTransactions() = 0;
-
-  /// Returns the ID the last globally known transaction.
-  virtual tx::TransactionId GlobalLast() const = 0;
-
-  /// Returns the ID of last locally known transaction.
-  virtual tx::TransactionId LocalLast() const = 0;
-
-  /// Returns the ID of the oldest transaction locally known to be active. It is
-  /// guaranteed that all the transactions older than the returned are globally
-  /// not active.
-  virtual TransactionId LocalOldestActive() const = 0;
-
-  /// Calls function f on each locally active transaction.
-  virtual void LocalForEachActiveTransaction(
-      std::function<void(Transaction &)> f) = 0;
-
-  /// Gets a transaction object for a running transaction.
-  virtual tx::Transaction *RunningTransaction(TransactionId tx_id) = 0;
-
-  /// Ensures the next transaction that starts will have the ID greater than
-  /// the given id.
-  virtual void EnsureNextIdGreater(TransactionId tx_id) = 0;
-
-  /// Garbage collects transactions older than tx_id from commit log.
-  virtual void GarbageCollectCommitLog(TransactionId tx_id) = 0;
-
-  auto &local_lock_graph() { return local_lock_graph_; }
-  const auto &local_lock_graph() const { return local_lock_graph_; }
-
- protected:
-  Transaction *CreateTransaction(TransactionId id, const Snapshot &snapshot) {
-    return new Transaction(id, snapshot, *this);
-  }
-
-  CommandId AdvanceCommand(Transaction *t) { return t->AdvanceCommand(); }
-
-  void SetCommand(Transaction *t, CommandId cid) { t->SetCommand(cid); }
-
- private:
-  // Map lock dependencies. Each entry maps (tx_that_wants_lock,
-  // tx_that_holds_lock). Used for local deadlock resolution.
-  // TODO consider global deadlock resolution.
-  ConcurrentMap<TransactionId, TransactionId> local_lock_graph_;
-};
-}  // namespace tx
+#ifdef MG_DISTRIBUTED
+#include "transactions/distributed/engine.hpp"
+#endif
diff --git a/src/transactions/single_node/engine_single_node.cpp b/src/transactions/single_node/engine.cpp
similarity index 72%
rename from src/transactions/single_node/engine_single_node.cpp
rename to src/transactions/single_node/engine.cpp
index 7037e2fb1..1e530b4ed 100644
--- a/src/transactions/single_node/engine_single_node.cpp
+++ b/src/transactions/single_node/engine.cpp
@@ -1,4 +1,4 @@
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 #include <limits>
 #include <mutex>
@@ -9,10 +9,9 @@
 
 namespace tx {
 
-EngineSingleNode::EngineSingleNode(durability::WriteAheadLog *wal)
-    : wal_(wal) {}
+Engine::Engine(durability::WriteAheadLog *wal) : wal_(wal) {}
 
-Transaction *EngineSingleNode::Begin() {
+Transaction *Engine::Begin() {
   VLOG(11) << "[Tx] Starting transaction " << counter_ + 1;
   std::lock_guard<utils::SpinLock> guard(lock_);
 
@@ -26,7 +25,7 @@ Transaction *EngineSingleNode::Begin() {
   return t;
 }
 
-CommandId EngineSingleNode::Advance(TransactionId id) {
+CommandId Engine::Advance(TransactionId id) {
   std::lock_guard<utils::SpinLock> guard(lock_);
 
   auto it = store_.find(id);
@@ -37,7 +36,7 @@ CommandId EngineSingleNode::Advance(TransactionId id) {
   return AdvanceCommand(t);
 }
 
-CommandId EngineSingleNode::UpdateCommand(TransactionId id) {
+CommandId Engine::UpdateCommand(TransactionId id) {
   std::lock_guard<utils::SpinLock> guard(lock_);
   auto it = store_.find(id);
   DCHECK(it != store_.end())
@@ -45,7 +44,7 @@ CommandId EngineSingleNode::UpdateCommand(TransactionId id) {
   return it->second->cid();
 }
 
-void EngineSingleNode::Commit(const Transaction &t) {
+void Engine::Commit(const Transaction &t) {
   VLOG(11) << "[Tx] Commiting transaction " << t.id_;
   std::lock_guard<utils::SpinLock> guard(lock_);
   clog_.set_committed(t.id_);
@@ -56,7 +55,7 @@ void EngineSingleNode::Commit(const Transaction &t) {
   store_.erase(store_.find(t.id_));
 }
 
-void EngineSingleNode::Abort(const Transaction &t) {
+void Engine::Abort(const Transaction &t) {
   VLOG(11) << "[Tx] Aborting transaction " << t.id_;
   std::lock_guard<utils::SpinLock> guard(lock_);
   clog_.set_aborted(t.id_);
@@ -67,11 +66,11 @@ void EngineSingleNode::Abort(const Transaction &t) {
   store_.erase(store_.find(t.id_));
 }
 
-CommitLog::Info EngineSingleNode::Info(TransactionId tx) const {
+CommitLog::Info Engine::Info(TransactionId tx) const {
   return clog_.fetch_info(tx);
 }
 
-Snapshot EngineSingleNode::GlobalGcSnapshot() {
+Snapshot Engine::GlobalGcSnapshot() {
   std::lock_guard<utils::SpinLock> guard(lock_);
 
   // No active transactions.
@@ -87,29 +86,29 @@ Snapshot EngineSingleNode::GlobalGcSnapshot() {
   return snapshot_copy;
 }
 
-Snapshot EngineSingleNode::GlobalActiveTransactions() {
+Snapshot Engine::GlobalActiveTransactions() {
   std::lock_guard<utils::SpinLock> guard(lock_);
   Snapshot active_transactions = active_;
   return active_transactions;
 }
 
-TransactionId EngineSingleNode::LocalLast() const {
+TransactionId Engine::LocalLast() const {
   std::lock_guard<utils::SpinLock> guard(lock_);
   return counter_;
 }
 
-TransactionId EngineSingleNode::GlobalLast() const { return LocalLast(); }
+TransactionId Engine::GlobalLast() const { return LocalLast(); }
 
-TransactionId EngineSingleNode::LocalOldestActive() const {
+TransactionId Engine::LocalOldestActive() const {
   std::lock_guard<utils::SpinLock> guard(lock_);
   return active_.empty() ? counter_ + 1 : active_.front();
 }
 
-void EngineSingleNode::GarbageCollectCommitLog(TransactionId tx_id) {
+void Engine::GarbageCollectCommitLog(TransactionId tx_id) {
   clog_.garbage_collect_older(tx_id);
 }
 
-void EngineSingleNode::LocalForEachActiveTransaction(
+void Engine::LocalForEachActiveTransaction(
     std::function<void(Transaction &)> f) {
   std::lock_guard<utils::SpinLock> guard(lock_);
   for (auto transaction : active_) {
@@ -117,7 +116,7 @@ void EngineSingleNode::LocalForEachActiveTransaction(
   }
 }
 
-Transaction *EngineSingleNode::RunningTransaction(TransactionId tx_id) {
+Transaction *Engine::RunningTransaction(TransactionId tx_id) {
   std::lock_guard<utils::SpinLock> guard(lock_);
   auto found = store_.find(tx_id);
   CHECK(found != store_.end())
@@ -125,7 +124,7 @@ Transaction *EngineSingleNode::RunningTransaction(TransactionId tx_id) {
   return found->second.get();
 }
 
-void EngineSingleNode::EnsureNextIdGreater(TransactionId tx_id) {
+void Engine::EnsureNextIdGreater(TransactionId tx_id) {
   std::lock_guard<utils::SpinLock> guard(lock_);
   counter_ = std::max(tx_id, counter_);
 }
diff --git a/src/transactions/single_node/engine.hpp b/src/transactions/single_node/engine.hpp
new file mode 100644
index 000000000..8d142fc33
--- /dev/null
+++ b/src/transactions/single_node/engine.hpp
@@ -0,0 +1,71 @@
+/// @file
+
+#pragma once
+
+#include <atomic>
+#include <experimental/optional>
+#include <unordered_map>
+
+#include "durability/single_node/wal.hpp"
+#include "transactions/commit_log.hpp"
+#include "transactions/transaction.hpp"
+#include "utils/thread/sync.hpp"
+
+namespace tx {
+
+/// Single-node deployment transaction engine. Has complete functionality.
+class Engine final {
+ public:
+  /// @param wal - Optional. If present, the Engine will write tx
+  /// Begin/Commit/Abort atomically (while under lock).
+  explicit Engine(durability::WriteAheadLog *wal = nullptr);
+
+  Engine(const Engine &) = delete;
+  Engine(Engine &&) = delete;
+  Engine &operator=(const Engine &) = delete;
+  Engine &operator=(Engine &&) = delete;
+
+  Transaction *Begin();
+  CommandId Advance(TransactionId id);
+  CommandId UpdateCommand(TransactionId id);
+  void Commit(const Transaction &t);
+  void Abort(const Transaction &t);
+  CommitLog::Info Info(TransactionId tx) const;
+  Snapshot GlobalGcSnapshot();
+  Snapshot GlobalActiveTransactions();
+  TransactionId GlobalLast() const;
+  TransactionId LocalLast() const;
+  TransactionId LocalOldestActive() const;
+  void LocalForEachActiveTransaction(std::function<void(Transaction &)> f);
+  Transaction *RunningTransaction(TransactionId tx_id);
+  void EnsureNextIdGreater(TransactionId tx_id);
+  void GarbageCollectCommitLog(TransactionId tx_id);
+
+  auto &local_lock_graph() { return local_lock_graph_; }
+  const auto &local_lock_graph() const { return local_lock_graph_; }
+
+ protected:
+  Transaction *CreateTransaction(TransactionId id, const Snapshot &snapshot) {
+    return new Transaction(id, snapshot, *this);
+  }
+
+  CommandId AdvanceCommand(Transaction *t) { return t->AdvanceCommand(); }
+
+  void SetCommand(Transaction *t, CommandId cid) { t->SetCommand(cid); }
+
+ private:
+  // Map lock dependencies. Each entry maps (tx_that_wants_lock,
+  // tx_that_holds_lock). Used for local deadlock resolution.
+  // TODO consider global deadlock resolution.
+  ConcurrentMap<TransactionId, TransactionId> local_lock_graph_;
+
+  TransactionId counter_{0};
+  CommitLog clog_;
+  std::unordered_map<TransactionId, std::unique_ptr<Transaction>> store_;
+  Snapshot active_;
+  mutable utils::SpinLock lock_;
+  // Optional. If present, the Engine will write tx Begin/Commit/Abort
+  // atomically (while under lock).
+  durability::WriteAheadLog *wal_{nullptr};
+};
+}  // namespace tx
diff --git a/src/transactions/single_node/engine_single_node.hpp b/src/transactions/single_node/engine_single_node.hpp
deleted file mode 100644
index 950369463..000000000
--- a/src/transactions/single_node/engine_single_node.hpp
+++ /dev/null
@@ -1,56 +0,0 @@
-/// @file
-
-#pragma once
-
-#include <atomic>
-#include <experimental/optional>
-#include <unordered_map>
-
-#include "durability/single_node/wal.hpp"
-#include "transactions/commit_log.hpp"
-#include "transactions/engine.hpp"
-#include "transactions/transaction.hpp"
-#include "utils/thread/sync.hpp"
-
-namespace tx {
-
-/// Single-node deployment transaction engine. Has complete functionality.
-class EngineSingleNode final : public Engine {
- public:
-  /// @param wal - Optional. If present, the Engine will write tx
-  /// Begin/Commit/Abort atomically (while under lock).
-  explicit EngineSingleNode(durability::WriteAheadLog *wal = nullptr);
-
-  EngineSingleNode(const EngineSingleNode &) = delete;
-  EngineSingleNode(EngineSingleNode &&) = delete;
-  EngineSingleNode &operator=(const EngineSingleNode &) = delete;
-  EngineSingleNode &operator=(EngineSingleNode &&) = delete;
-
-  Transaction *Begin() override;
-  CommandId Advance(TransactionId id) override;
-  CommandId UpdateCommand(TransactionId id) override;
-  void Commit(const Transaction &t) override;
-  void Abort(const Transaction &t) override;
-  CommitLog::Info Info(TransactionId tx) const override;
-  Snapshot GlobalGcSnapshot() override;
-  Snapshot GlobalActiveTransactions() override;
-  TransactionId GlobalLast() const override;
-  TransactionId LocalLast() const override;
-  TransactionId LocalOldestActive() const override;
-  void LocalForEachActiveTransaction(
-      std::function<void(Transaction &)> f) override;
-  Transaction *RunningTransaction(TransactionId tx_id) override;
-  void EnsureNextIdGreater(TransactionId tx_id) override;
-  void GarbageCollectCommitLog(TransactionId tx_id) override;
-
- private:
-  TransactionId counter_{0};
-  CommitLog clog_;
-  std::unordered_map<TransactionId, std::unique_ptr<Transaction>> store_;
-  Snapshot active_;
-  mutable utils::SpinLock lock_;
-  // Optional. If present, the Engine will write tx Begin/Commit/Abort
-  // atomically (while under lock).
-  durability::WriteAheadLog *wal_{nullptr};
-};
-}  // namespace tx
diff --git a/tests/benchmark/expansion.cpp b/tests/benchmark/expansion.cpp
index 8d3596ae2..62ae08bce 100644
--- a/tests/benchmark/expansion.cpp
+++ b/tests/benchmark/expansion.cpp
@@ -12,7 +12,7 @@ class ExpansionBenchFixture : public benchmark::Fixture {
  protected:
   // GraphDb shouldn't be global constructed/destructed. See
   // documentation in database/single_node/graph_db.hpp for details.
-  std::experimental::optional<database::SingleNode> db_;
+  std::experimental::optional<database::GraphDb> db_;
   query::Interpreter interpreter_;
 
   void SetUp(const benchmark::State &state) override {
diff --git a/tests/benchmark/mvcc.cpp b/tests/benchmark/mvcc.cpp
index 8b7f23b5a..a79d59a87 100644
--- a/tests/benchmark/mvcc.cpp
+++ b/tests/benchmark/mvcc.cpp
@@ -4,7 +4,7 @@
 
 #include "mvcc/single_node/record.hpp"
 #include "mvcc/single_node/version_list.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 class Prop : public mvcc::Record<Prop> {
  public:
@@ -19,7 +19,7 @@ class Prop : public mvcc::Record<Prop> {
 void MvccMix(benchmark::State &state) {
   while (state.KeepRunning()) {
     state.PauseTiming();
-    tx::EngineSingleNode engine;
+    tx::Engine engine;
     auto t1 = engine.Begin();
     mvcc::VersionList<Prop> version_list(*t1, 0, 0);
 
diff --git a/tests/benchmark/query/planner.cpp b/tests/benchmark/query/planner.cpp
index 9b39941d5..2f0f4833a 100644
--- a/tests/benchmark/query/planner.cpp
+++ b/tests/benchmark/query/planner.cpp
@@ -31,7 +31,7 @@ static void AddChainedMatches(int num_matches, query::AstStorage &storage) {
 }
 
 static void BM_PlanChainedMatches(benchmark::State &state) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   while (state.KeepRunning()) {
     state.PauseTiming();
@@ -101,7 +101,7 @@ static auto CreateIndexedVertices(int index_count, int vertex_count,
 }
 
 static void BM_PlanAndEstimateIndexedMatching(benchmark::State &state) {
-  database::SingleNode db;
+  database::GraphDb db;
   storage::Label label;
   storage::Property prop;
   int index_count = state.range(0);
@@ -134,7 +134,7 @@ static void BM_PlanAndEstimateIndexedMatching(benchmark::State &state) {
 
 static void BM_PlanAndEstimateIndexedMatchingWithCachedCounts(
     benchmark::State &state) {
-  database::SingleNode db;
+  database::GraphDb db;
   storage::Label label;
   storage::Property prop;
   int index_count = state.range(0);
diff --git a/tests/benchmark/tx_engine.cpp b/tests/benchmark/tx_engine.cpp
index a2a14d746..d3433b191 100644
--- a/tests/benchmark/tx_engine.cpp
+++ b/tests/benchmark/tx_engine.cpp
@@ -3,14 +3,14 @@
 
 #include <glog/logging.h>
 
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "utils/timer.hpp"
 
 void Benchmark(int64_t num_threads, int64_t num_transactions) {
   LOG(INFO) << "Testing with " << num_threads << " threads and "
             << num_transactions << " transactions per thread...";
 
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
   std::vector<std::thread> threads;
   utils::Timer timer;
   for (int i = 0; i < num_threads; ++i) {
diff --git a/tests/feature_benchmark/kafka/benchmark.cpp b/tests/feature_benchmark/kafka/benchmark.cpp
index d864e2d6b..237d18738 100644
--- a/tests/feature_benchmark/kafka/benchmark.cpp
+++ b/tests/feature_benchmark/kafka/benchmark.cpp
@@ -30,7 +30,7 @@ DEFINE_string(output_file, "", "Output file where shold the results be.");
 void KafkaBenchmarkMain() {
   google::SetUsageMessage("Memgraph kafka benchmark database server");
   query::Interpreter interpreter;
-  database::SingleNode db;
+  database::GraphDb db;
   SessionData session_data{&db, &interpreter};
 
   std::atomic<int64_t> query_counter{0};
diff --git a/tests/manual/query_planner.cpp b/tests/manual/query_planner.cpp
index eabcddfeb..364731bf9 100644
--- a/tests/manual/query_planner.cpp
+++ b/tests/manual/query_planner.cpp
@@ -553,7 +553,7 @@ int main(int argc, char *argv[]) {
     std::cerr << "File '" << in_db_filename << "' does not exist!" << std::endl;
     std::exit(EXIT_FAILURE);
   }
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   Timer planning_timer;
   InteractiveDbAccessor interactive_db(
diff --git a/tests/manual/repl.cpp b/tests/manual/repl.cpp
index e1e021771..96c766997 100644
--- a/tests/manual/repl.cpp
+++ b/tests/manual/repl.cpp
@@ -75,7 +75,7 @@ int main(int argc, char *argv[]) {
   // TODO switch to GFlags, once finally available
   if (argc > 3) google::InitGoogleLogging(argv[0]);
 
-  database::SingleNode db;
+  database::GraphDb db;
   std::cout << "Generating graph..." << std::endl;
   //  fill_db;
   random_generate(db, node_count, edge_count);
diff --git a/tests/manual/single_query.cpp b/tests/manual/single_query.cpp
index b10d8849e..0f8274695 100644
--- a/tests/manual/single_query.cpp
+++ b/tests/manual/single_query.cpp
@@ -11,7 +11,7 @@ int main(int argc, char *argv[]) {
     std::cout << "Usage: ./single_query 'RETURN \"query here\"'" << std::endl;
     exit(1);
   }
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   ResultStreamFaker<query::TypedValue> stream;
   auto results = query::Interpreter()(argv[1], *dba, {}, false);
diff --git a/tests/property_based/random_graph.cpp b/tests/property_based/random_graph.cpp
index 15b0c528e..705e2477c 100644
--- a/tests/property_based/random_graph.cpp
+++ b/tests/property_based/random_graph.cpp
@@ -24,7 +24,7 @@ RC_GTEST_PROP(RandomGraph, RandomGraph, (std::vector<std::string> vertex_labels,
   int vertices_num = vertex_labels.size();
   int edges_num = edge_types.size();
 
-  database::SingleNode db;
+  database::GraphDb db;
   std::vector<VertexAccessor> vertices;
   std::unordered_map<VertexAccessor, std::string> vertex_label_map;
   std::unordered_map<EdgeAccessor, std::string> edge_type_map;
diff --git a/tests/unit/bfs_single_node.cpp b/tests/unit/bfs_single_node.cpp
index 998bc33f6..8f761b6b6 100644
--- a/tests/unit/bfs_single_node.cpp
+++ b/tests/unit/bfs_single_node.cpp
@@ -60,7 +60,7 @@ class SingleNodeDb : public Database {
   }
 
  protected:
-  database::SingleNode db_;
+  database::GraphDb db_;
 };
 
 class SingleNodeBfsTest
diff --git a/tests/unit/bolt_encoder.cpp b/tests/unit/bolt_encoder.cpp
index d6510a316..c8a6c02da 100644
--- a/tests/unit/bolt_encoder.cpp
+++ b/tests/unit/bolt_encoder.cpp
@@ -164,7 +164,7 @@ TEST(BoltEncoder, VertexAndEdge) {
   output.clear();
 
   // create vertex
-  database::SingleNode db;
+  database::GraphDb db;
   auto db_accessor = db.Access();
   auto va1 = db_accessor->InsertVertex();
   auto va2 = db_accessor->InsertVertex();
diff --git a/tests/unit/concurrent_id_mapper_single_node.cpp b/tests/unit/concurrent_id_mapper_single_node.cpp
index 6f84dcd34..87090b04d 100644
--- a/tests/unit/concurrent_id_mapper_single_node.cpp
+++ b/tests/unit/concurrent_id_mapper_single_node.cpp
@@ -6,10 +6,10 @@
 #include <gtest/gtest.h>
 
 #include "storage/common/types.hpp"
-#include "storage/single_node/concurrent_id_mapper_single_node.hpp"
+#include "storage/single_node/concurrent_id_mapper.hpp"
 
 using IdLabel = storage::Label;
-using MapperLabel = storage::SingleNodeConcurrentIdMapper<IdLabel>;
+using MapperLabel = storage::ConcurrentIdMapper<IdLabel>;
 
 TEST(ConcurrentIdMapper, SameValueGivesSameId) {
   MapperLabel mapper;
@@ -54,7 +54,7 @@ TEST(ConcurrentIdMapper, SameIdReturnedMultipleThreads) {
 }
 
 using IdProperty = storage::Property;
-using MapperProperty = storage::SingleNodeConcurrentIdMapper<IdProperty>;
+using MapperProperty = storage::ConcurrentIdMapper<IdProperty>;
 
 TEST(ConcurrentIdMapper, PropertyLocation) {
   // TODO(ipaljak): write unit tests for storage::Common and all
diff --git a/tests/unit/cypher_main_visitor.cpp b/tests/unit/cypher_main_visitor.cpp
index 80a608f57..e949e879e 100644
--- a/tests/unit/cypher_main_visitor.cpp
+++ b/tests/unit/cypher_main_visitor.cpp
@@ -35,7 +35,7 @@ using testing::UnorderedElementsAre;
 class Base {
  public:
   explicit Base(const std::string &query) : query_string_(query) {}
-  database::SingleNode db_;
+  database::GraphDb db_;
   std::unique_ptr<database::GraphDbAccessor> db_accessor_{db_.Access()};
   ParsingContext context_;
   Parameters parameters_;
diff --git a/tests/unit/database_key_index.cpp b/tests/unit/database_key_index.cpp
index 34a605dec..0b61f491e 100644
--- a/tests/unit/database_key_index.cpp
+++ b/tests/unit/database_key_index.cpp
@@ -5,7 +5,7 @@
 #include "database/single_node/graph_db_accessor.hpp"
 #include "storage/common/types.hpp"
 #include "storage/single_node/vertex.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 #include "mvcc_gc_common.hpp"
 
@@ -14,9 +14,9 @@ using testing::UnorderedElementsAreArray;
 // Test index does it insert everything uniquely
 TEST(LabelsIndex, UniqueInsert) {
   database::KeyIndex<storage::Label, Vertex> index;
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
 
   auto t1 = engine.Begin();
   mvcc::VersionList<Vertex> vlist(*t1, 0, 0);
@@ -42,10 +42,10 @@ TEST(LabelsIndex, UniqueInsert) {
 
 // Check if index filters duplicates.
 TEST(LabelsIndex, UniqueFilter) {
-  database::SingleNode db;
+  database::GraphDb db;
   database::KeyIndex<storage::Label, Vertex> index;
   auto dba = db.Access();
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
 
   auto t1 = engine.Begin();
   mvcc::VersionList<Vertex> vlist1(*t1, 0, 0);
@@ -83,9 +83,9 @@ TEST(LabelsIndex, UniqueFilter) {
 // Delete not anymore relevant recods from index.
 TEST(LabelsIndex, Refresh) {
   database::KeyIndex<storage::Label, Vertex> index;
-  database::SingleNode db;
+  database::GraphDb db;
   auto access = db.Access();
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
 
   // add two vertices to  database
   auto t1 = engine.Begin();
@@ -122,7 +122,7 @@ TEST(LabelsIndex, Refresh) {
 
 // Transaction hasn't ended and so the vertex is not visible.
 TEST(LabelsIndexDb, AddGetZeroLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto vertex = dba->InsertVertex();
   vertex.add_label(dba->Label("test"));
@@ -135,7 +135,7 @@ TEST(LabelsIndexDb, AddGetZeroLabels) {
 // Test label index by adding and removing one vertex, and removing label from
 // another, while the third one with an irrelevant label exists.
 TEST(LabelsIndexDb, AddGetRemoveLabel) {
-  database::SingleNode db;
+  database::GraphDb db;
   {
     auto dba = db.Access();
 
diff --git a/tests/unit/database_label_property_index.cpp b/tests/unit/database_label_property_index.cpp
index a61ee71f2..947b0dbac 100644
--- a/tests/unit/database_label_property_index.cpp
+++ b/tests/unit/database_label_property_index.cpp
@@ -4,7 +4,7 @@
 #include "database/single_node/graph_db_accessor.hpp"
 #include "storage/common/types.hpp"
 #include "storage/single_node/indexes/label_property_index.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 #include "mvcc_gc_common.hpp"
 
@@ -42,11 +42,11 @@ class LabelPropertyIndexComplexTest : public ::testing::Test {
   }
 
  public:
-  SingleNode db_;
+  GraphDb db_;
   LabelPropertyIndex index;
   LabelPropertyIndex::Key *key;
 
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
   tx::Transaction *t{nullptr};
 
   mvcc::VersionList<Vertex> *vlist;
@@ -59,7 +59,7 @@ class LabelPropertyIndexComplexTest : public ::testing::Test {
 };
 
 TEST(LabelPropertyIndex, CreateIndex) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
   LabelPropertyIndex::Key key(accessor->Label("test"),
                               accessor->Property("test2"));
@@ -69,7 +69,7 @@ TEST(LabelPropertyIndex, CreateIndex) {
 }
 
 TEST(LabelPropertyIndex, DeleteIndex) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
   LabelPropertyIndex::Key key(accessor->Label("test"),
                               accessor->Property("test2"));
@@ -81,7 +81,7 @@ TEST(LabelPropertyIndex, DeleteIndex) {
 }
 
 TEST(LabelPropertyIndex, IndexExistance) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
   LabelPropertyIndex::Key key(accessor->Label("test"),
                               accessor->Property("test2"));
@@ -94,7 +94,7 @@ TEST(LabelPropertyIndex, IndexExistance) {
 }
 
 TEST(LabelPropertyIndex, Count) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
   auto label = accessor->Label("label");
   auto property = accessor->Property("property");
diff --git a/tests/unit/database_transaction_timeout.cpp b/tests/unit/database_transaction_timeout.cpp
index d4db622cd..0c899fe1a 100644
--- a/tests/unit/database_transaction_timeout.cpp
+++ b/tests/unit/database_transaction_timeout.cpp
@@ -9,7 +9,7 @@ DECLARE_int32(query_execution_time_sec);
 
 TEST(TransactionTimeout, TransactionTimeout) {
   FLAGS_query_execution_time_sec = 3;
-  database::SingleNode db;
+  database::GraphDb db;
   query::Interpreter interpreter;
   auto interpret = [&](auto &dba, const std::string &query) {
     ResultStreamFaker<query::TypedValue> stream;
diff --git a/tests/unit/durability.cpp b/tests/unit/durability.cpp
index e808ba008..22a239c1d 100644
--- a/tests/unit/durability.cpp
+++ b/tests/unit/durability.cpp
@@ -343,7 +343,7 @@ TEST_F(Durability, WalEncoding) {
   {
     auto config = DbConfig();
     config.durability_enabled = true;
-    database::SingleNode db{config};
+    database::GraphDb db{config};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     ASSERT_EQ(v0.gid(), gid0);
@@ -418,7 +418,7 @@ TEST_F(Durability, SnapshotEncoding) {
   auto gid1 = generator.Next();
   auto gid2 = generator.Next();
   {
-    database::SingleNode db{DbConfig()};
+    database::GraphDb db{DbConfig()};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     ASSERT_EQ(v0.gid(), gid0);
@@ -532,7 +532,7 @@ TEST_F(Durability, SnapshotEncoding) {
 }
 
 TEST_F(Durability, SnapshotRecovery) {
-  database::SingleNode db{DbConfig()};
+  database::GraphDb db{DbConfig()};
   MakeDb(db, 300, {0, 1, 2});
   MakeDb(db, 300);
   MakeDb(db, 300, {3, 4});
@@ -540,13 +540,13 @@ TEST_F(Durability, SnapshotRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     CompareDbs(db, recovered);
   }
 }
 
 TEST_F(Durability, SnapshotNoVerticesIdRecovery) {
-  database::SingleNode db{DbConfig()};
+  database::GraphDb db{DbConfig()};
   MakeDb(db, 10);
 
   // Erase all vertices, this should cause snapshot to not have any more
@@ -562,7 +562,7 @@ TEST_F(Durability, SnapshotNoVerticesIdRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     EXPECT_EQ(db.storage().VertexGenerator().LocalCount(),
               recovered.storage().VertexGenerator().LocalCount());
     EXPECT_EQ(db.storage().EdgeGenerator().LocalCount(),
@@ -573,7 +573,7 @@ TEST_F(Durability, SnapshotNoVerticesIdRecovery) {
 TEST_F(Durability, SnapshotAndWalIdRecovery) {
   auto config = DbConfig();
   config.durability_enabled = true;
-  database::SingleNode db{config};
+  database::GraphDb db{config};
   MakeDb(db, 300);
   MakeSnapshot(0, db);
   MakeDb(db, 300);
@@ -583,7 +583,7 @@ TEST_F(Durability, SnapshotAndWalIdRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     EXPECT_EQ(db.storage().VertexGenerator().LocalCount(),
               recovered.storage().VertexGenerator().LocalCount());
     EXPECT_EQ(db.storage().EdgeGenerator().LocalCount(),
@@ -594,7 +594,7 @@ TEST_F(Durability, SnapshotAndWalIdRecovery) {
 TEST_F(Durability, OnlyWalIdRecovery) {
   auto config = DbConfig();
   config.durability_enabled = true;
-  database::SingleNode db{config};
+  database::GraphDb db{config};
   MakeDb(db, 300);
   db.wal().Flush();
   ASSERT_EQ(DirFiles(snapshot_dir_).size(), 0);
@@ -602,7 +602,7 @@ TEST_F(Durability, OnlyWalIdRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     EXPECT_EQ(db.storage().VertexGenerator().LocalCount(),
               recovered.storage().VertexGenerator().LocalCount());
     EXPECT_EQ(db.storage().EdgeGenerator().LocalCount(),
@@ -621,7 +621,7 @@ TEST_F(Durability, WalRecovery) {
   for (auto &synchronous_commit : {false, true}) {
     CleanDurability();
     auto config = modify_config(DbConfig(), true, synchronous_commit);
-    database::SingleNode db{config};
+    database::GraphDb db{config};
     MakeDb(db, 100, {0, 1, 2});
     MakeDb(db, 100);
     MakeDb(db, 100, {3, 4});
@@ -637,7 +637,7 @@ TEST_F(Durability, WalRecovery) {
     {
       auto recovered_config = DbConfig();
       recovered_config.db_recover_on_startup = true;
-      database::SingleNode recovered{recovered_config};
+      database::GraphDb recovered{recovered_config};
       CompareDbs(db, recovered);
     }
   }
@@ -646,7 +646,7 @@ TEST_F(Durability, WalRecovery) {
 TEST_F(Durability, SnapshotAndWalRecovery) {
   auto config = DbConfig();
   config.durability_enabled = true;
-  database::SingleNode db{config};
+  database::GraphDb db{config};
   MakeDb(db, 300, {0, 1, 2});
   MakeDb(db, 300);
   MakeSnapshot(0, db);
@@ -661,7 +661,7 @@ TEST_F(Durability, SnapshotAndWalRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     CompareDbs(db, recovered);
   }
 }
@@ -669,7 +669,7 @@ TEST_F(Durability, SnapshotAndWalRecovery) {
 TEST_F(Durability, SnapshotAndWalRecoveryAfterComplexTxSituation) {
   auto config = DbConfig();
   config.durability_enabled = true;
-  database::SingleNode db{config};
+  database::GraphDb db{config};
 
   // The first transaction modifies and commits.
   auto dba_1 = db.Access();
@@ -711,7 +711,7 @@ TEST_F(Durability, SnapshotAndWalRecoveryAfterComplexTxSituation) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     ASSERT_EQ(VisibleVertexCount(recovered), 400);
     CompareDbs(db, recovered);
   }
@@ -722,7 +722,7 @@ TEST_F(Durability, NoWalDuringRecovery) {
   {
     auto config = DbConfig();
     config.durability_enabled = true;
-    database::SingleNode db{config};
+    database::GraphDb db{config};
     MakeDb(db, 300, {0, 1, 2});
 
     db.wal().Flush();
@@ -732,13 +732,13 @@ TEST_F(Durability, NoWalDuringRecovery) {
   {
     auto recovered_config = DbConfig();
     recovered_config.db_recover_on_startup = true;
-    database::SingleNode recovered{recovered_config};
+    database::GraphDb recovered{recovered_config};
     EXPECT_EQ(DirFiles(wal_dir_).size(), wal_files_before);
   }
 }
 
 TEST_F(Durability, SnapshotRetention) {
-  database::SingleNode db{DbConfig()};
+  database::GraphDb db{DbConfig()};
   for (auto &pair : {std::pair<int, int>{5, 10}, {5, 3}, {7, -1}}) {
     CleanDurability();
     int count, retain;
@@ -765,7 +765,7 @@ TEST_F(Durability, WalRetention) {
   {
     auto config = DbConfig();
     config.durability_enabled = true;
-    database::SingleNode db{config};
+    database::GraphDb db{config};
     MakeDb(db, 100);
     MakeSnapshot(0, db);
     MakeDb(db, 100);
@@ -788,7 +788,7 @@ TEST_F(Durability, SnapshotOnExit) {
   {
     auto config = DbConfig();
     config.snapshot_on_exit = true;
-    database::SingleNode graph_db{config};
+    database::GraphDb graph_db{config};
   }
   EXPECT_EQ(DirFiles(snapshot_dir_).size(), 1);
 }
@@ -877,7 +877,7 @@ TEST_F(Durability, SequentialRecovery) {
   };
 
   auto make_updates = [&run_updates, this](
-      database::SingleNode &db, bool snapshot_during, bool snapshot_after) {
+      database::GraphDb &db, bool snapshot_during, bool snapshot_after) {
     std::atomic<bool> keep_running{true};
     auto update_theads = run_updates(db, keep_running);
     std::this_thread::sleep_for(25ms);
@@ -899,7 +899,7 @@ TEST_F(Durability, SequentialRecovery) {
     CleanDurability();
     auto config = DbConfig();
     config.durability_enabled = true;
-    database::SingleNode db{config};
+    database::GraphDb db{config};
     init_db(db);
     make_updates(db, combo.first, combo.second);
 
@@ -907,12 +907,12 @@ TEST_F(Durability, SequentialRecovery) {
       auto recovered_config = DbConfig();
       recovered_config.db_recover_on_startup = true;
       recovered_config.durability_enabled = true;
-      database::SingleNode recovered{recovered_config};
+      database::GraphDb recovered{recovered_config};
       CompareDbs(db, recovered);
       {
         for (auto &combo2 : combinations) {
           make_updates(recovered, combo2.first, combo2.second);
-          database::SingleNode recovered_2{recovered_config};
+          database::GraphDb recovered_2{recovered_config};
           CompareDbs(recovered, recovered_2);
         }
       }
@@ -923,7 +923,7 @@ TEST_F(Durability, SequentialRecovery) {
 TEST_F(Durability, ContainsDurabilityFilesSnapshot) {
   ASSERT_FALSE(durability::ContainsDurabilityFiles(durability_dir_));
   {
-    database::SingleNode db{DbConfig()};
+    database::GraphDb db{DbConfig()};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     MakeSnapshot(0, db);
@@ -934,7 +934,7 @@ TEST_F(Durability, ContainsDurabilityFilesSnapshot) {
 TEST_F(Durability, ContainsDurabilityFilesWal) {
   ASSERT_FALSE(durability::ContainsDurabilityFiles(durability_dir_));
   {
-    database::SingleNode db{DbConfig(true, false)};
+    database::GraphDb db{DbConfig(true, false)};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     dba->Commit();
@@ -946,21 +946,21 @@ TEST_F(Durability, ContainsDurabilityFilesWal) {
 TEST_F(Durability, MoveToBackupSnapshot) {
   ASSERT_FALSE(durability::ContainsDurabilityFiles(backup_dir_));
   {
-    database::SingleNode db{DbConfig()};
+    database::GraphDb db{DbConfig()};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     MakeSnapshot(0, db);
   }
 
   // durability-enabled=true, db-recover-on-startup=false
-  database::SingleNode db{DbConfig(true, false)};
+  database::GraphDb db{DbConfig(true, false)};
   ASSERT_TRUE(durability::ContainsDurabilityFiles(backup_dir_));
 }
 
 TEST_F(Durability, MoveToBackupWal) {
   ASSERT_FALSE(durability::ContainsDurabilityFiles(backup_dir_));
   {
-    database::SingleNode db{DbConfig(true, false)};
+    database::GraphDb db{DbConfig(true, false)};
     auto dba = db.Access();
     auto v0 = dba->InsertVertex();
     dba->Commit();
@@ -968,6 +968,6 @@ TEST_F(Durability, MoveToBackupWal) {
   }
 
   // durability-enabled=true, db-recover-on-startup=false
-  database::SingleNode db{DbConfig(true, false)};
+  database::GraphDb db{DbConfig(true, false)};
   ASSERT_TRUE(durability::ContainsDurabilityFiles(backup_dir_));
 }
diff --git a/tests/unit/graph_db.cpp b/tests/unit/graph_db.cpp
index ae62b749a..8238e1134 100644
--- a/tests/unit/graph_db.cpp
+++ b/tests/unit/graph_db.cpp
@@ -10,7 +10,7 @@
 TEST(GraphDbTest, GarbageCollectIndices) {
   database::Config config;
   config.gc_cycle_sec = -1;
-  database::SingleNode graph_db{config};
+  database::GraphDb graph_db{config};
   std::unique_ptr<database::GraphDbAccessor> dba = graph_db.Access();
 
   auto commit = [&] {
diff --git a/tests/unit/graph_db_accessor.cpp b/tests/unit/graph_db_accessor.cpp
index 047a9290c..963169384 100644
--- a/tests/unit/graph_db_accessor.cpp
+++ b/tests/unit/graph_db_accessor.cpp
@@ -17,7 +17,7 @@ auto Count(TIterable iterable) {
 }
 
 TEST(GraphDbAccessorTest, InsertVertex) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
   gid::Generator generator(0);
 
@@ -37,7 +37,7 @@ TEST(GraphDbAccessorTest, InsertVertex) {
 }
 
 TEST(GraphDbAccessorTest, UniqueVertexId) {
-  SingleNode db;
+  GraphDb db;
   SkipList<int64_t> ids;
 
   std::vector<std::thread> threads;
@@ -54,7 +54,7 @@ TEST(GraphDbAccessorTest, UniqueVertexId) {
 }
 
 TEST(GraphDbAccessorTest, RemoveVertexSameTransaction) {
-  SingleNode db;
+  GraphDb db;
   auto accessor = db.Access();
 
   EXPECT_EQ(Count(accessor->Vertices(false)), 0);
@@ -72,7 +72,7 @@ TEST(GraphDbAccessorTest, RemoveVertexSameTransaction) {
 }
 
 TEST(GraphDbAccessorTest, RemoveVertexDifferentTransaction) {
-  SingleNode db;
+  GraphDb db;
   // first transaction creates a vertex
   {
     auto accessor = db.Access();
@@ -97,7 +97,7 @@ TEST(GraphDbAccessorTest, RemoveVertexDifferentTransaction) {
 }
 
 TEST(GraphDbAccessorTest, InsertEdge) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   auto va1 = dba->InsertVertex();
@@ -139,7 +139,7 @@ TEST(GraphDbAccessorTest, InsertEdge) {
 }
 
 TEST(GraphDbAccessorTest, UniqueEdgeId) {
-  SingleNode db;
+  GraphDb db;
   SkipList<int64_t> ids;
 
   std::vector<std::thread> threads;
@@ -160,7 +160,7 @@ TEST(GraphDbAccessorTest, UniqueEdgeId) {
 }
 
 TEST(GraphDbAccessorTest, RemoveEdge) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   // setup (v1) - [:likes] -> (v2) <- [:hates] - (v3)
@@ -207,7 +207,7 @@ TEST(GraphDbAccessorTest, RemoveEdge) {
 }
 
 TEST(GraphDbAccessorTest, DetachRemoveVertex) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   // setup (v0)- []->(v1)<-[]-(v2)<-[]-(v3)
@@ -281,7 +281,7 @@ TEST(GraphDbAccessorTest, DetachRemoveVertexMultiple) {
   // This test checks that we can detach remove the
   // same vertex / edge multiple times
 
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   // setup: make a fully connected N graph
@@ -324,7 +324,7 @@ TEST(GraphDbAccessorTest, DetachRemoveVertexMultiple) {
 }
 
 TEST(GraphDbAccessorTest, Labels) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   Label label_friend = dba->Label("friend");
@@ -338,7 +338,7 @@ TEST(GraphDbAccessorTest, Labels) {
 }
 
 TEST(GraphDbAccessorTest, EdgeTypes) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   EdgeType edge_type = dba->EdgeType("likes");
@@ -352,7 +352,7 @@ TEST(GraphDbAccessorTest, EdgeTypes) {
 }
 
 TEST(GraphDbAccessorTest, Properties) {
-  SingleNode db;
+  GraphDb db;
   auto dba = db.Access();
 
   Property prop = dba->Property("name");
@@ -366,7 +366,7 @@ TEST(GraphDbAccessorTest, Properties) {
 }
 
 TEST(GraphDbAccessorTest, Transfer) {
-  SingleNode db;
+  GraphDb db;
 
   auto dba1 = db.Access();
   auto prop = dba1->Property("property");
diff --git a/tests/unit/graph_db_accessor_index_api.cpp b/tests/unit/graph_db_accessor_index_api.cpp
index 59d14e2b1..a51d16e8b 100644
--- a/tests/unit/graph_db_accessor_index_api.cpp
+++ b/tests/unit/graph_db_accessor_index_api.cpp
@@ -22,7 +22,7 @@ auto Count(TIterable iterable) {
  */
 class GraphDbAccessorIndex : public testing::Test {
  protected:
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba{db.Access()};
   storage::Property property = dba->Property("property");
   storage::Label label = dba->Label("label");
@@ -137,7 +137,7 @@ TEST_F(GraphDbAccessorIndex, LabelPropertyIndexCount) {
 TEST(GraphDbAccessorIndexApi, LabelPropertyBuildIndexConcurrent) {
   const int ITER_COUNT = 10;
   for (int iter = 0; iter < ITER_COUNT; ++iter) {
-    database::SingleNode db;
+    database::GraphDb db;
     const int THREAD_COUNT = 10;
     std::vector<std::thread> threads;
     for (int index = 0; index < THREAD_COUNT; ++index) {
diff --git a/tests/unit/interpreter.cpp b/tests/unit/interpreter.cpp
index 46e351ebc..41a3e5d4d 100644
--- a/tests/unit/interpreter.cpp
+++ b/tests/unit/interpreter.cpp
@@ -14,7 +14,7 @@
 
 class InterpreterTest : public ::testing::Test {
  protected:
-  database::SingleNode db_;
+  database::GraphDb db_;
   query::Interpreter interpreter_;
 
   auto Interpret(const std::string &query,
diff --git a/tests/unit/mvcc.cpp b/tests/unit/mvcc.cpp
index 358a81906..55027db1b 100644
--- a/tests/unit/mvcc.cpp
+++ b/tests/unit/mvcc.cpp
@@ -5,14 +5,14 @@
 #include "mvcc/common/version.hpp"
 #include "mvcc/single_node/record.hpp"
 #include "mvcc/single_node/version_list.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "transactions/transaction.hpp"
 #include "utils/thread/sync.hpp"
 
 #include "mvcc_gc_common.hpp"
 
 TEST(MVCC, Deadlock) {
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
 
   auto t0 = engine.Begin();
   mvcc::VersionList<Prop> version_list1(*t0, 0, 0);
@@ -32,7 +32,7 @@ TEST(MVCC, Deadlock) {
 TEST(MVCC, UpdateDontDelete) {
   std::atomic<int> count{0};
   {
-    tx::EngineSingleNode engine;
+    tx::Engine engine;
     auto t1 = engine.Begin();
     mvcc::VersionList<DestrCountRec> version_list(*t1, 0, 0, count);
     engine.Commit(*t1);
@@ -56,7 +56,7 @@ TEST(MVCC, UpdateDontDelete) {
 
 // Check that we get the oldest record.
 TEST(MVCC, Oldest) {
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
   auto t1 = engine.Begin();
   mvcc::VersionList<Prop> version_list(*t1, 0, 0);
   auto first = version_list.Oldest();
diff --git a/tests/unit/mvcc_find_update_common.hpp b/tests/unit/mvcc_find_update_common.hpp
index 64ab1d75d..b03236c88 100644
--- a/tests/unit/mvcc_find_update_common.hpp
+++ b/tests/unit/mvcc_find_update_common.hpp
@@ -5,7 +5,7 @@
 #include "mvcc/common/version.hpp"
 #include "mvcc/single_node/record.hpp"
 #include "mvcc/single_node/version_list.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "transactions/transaction.hpp"
 
 class TestClass : public mvcc::Record<TestClass> {
@@ -58,7 +58,7 @@ class Mvcc : public ::testing::Test {
   }
   // variable where number of versions is stored
   int version_list_size = 0;
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
   tx::Transaction *t1 = engine.Begin();
   mvcc::VersionList<TestClass> version_list{*t1, 0, 0, version_list_size};
   TestClass *v1 = nullptr;
diff --git a/tests/unit/mvcc_gc.cpp b/tests/unit/mvcc_gc.cpp
index a2dbdb0d6..29e833251 100644
--- a/tests/unit/mvcc_gc.cpp
+++ b/tests/unit/mvcc_gc.cpp
@@ -11,13 +11,13 @@
 #include "mvcc/single_node/version_list.hpp"
 #include "storage/single_node/garbage_collector.hpp"
 #include "storage/single_node/vertex.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 #include "mvcc_gc_common.hpp"
 
 class MvccGcTest : public ::testing::Test {
  protected:
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
 
  private:
   tx::Transaction *t0 = engine.Begin();
@@ -115,7 +115,7 @@ TEST_F(MvccGcTest, OldestTransactionSnapshot) {
  */
 TEST(GarbageCollector, GcClean) {
   ConcurrentMap<int64_t, mvcc::VersionList<DestrCountRec> *> collection;
-  tx::EngineSingleNode engine;
+  tx::Engine engine;
   DeferredDeleter<DestrCountRec> deleter;
   DeferredDeleter<mvcc::VersionList<DestrCountRec>> vlist_deleter;
   GarbageCollector<decltype(collection), DestrCountRec> gc(collection, deleter,
diff --git a/tests/unit/mvcc_gc_common.hpp b/tests/unit/mvcc_gc_common.hpp
index f3930ee55..d4386ddc6 100644
--- a/tests/unit/mvcc_gc_common.hpp
+++ b/tests/unit/mvcc_gc_common.hpp
@@ -1,7 +1,7 @@
 #pragma once
 
 #include "mvcc/single_node/record.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 
 /**
  * @brief - Empty class which inherits from mvcc:Record.
@@ -29,7 +29,7 @@ class DestrCountRec : public mvcc::Record<DestrCountRec> {
 // helper function for creating a GC snapshot
 // if given a nullptr it makes a GC snapshot like there
 // are no active transactions
-auto GcSnapshot(tx::EngineSingleNode &engine, tx::Transaction *t) {
+auto GcSnapshot(tx::Engine &engine, tx::Transaction *t) {
   if (t != nullptr) {
     tx::Snapshot gc_snap = t->snapshot();
     gc_snap.insert(t->id_);
diff --git a/tests/unit/query_common.hpp b/tests/unit/query_common.hpp
index 1056e86d8..9bf8c31ab 100644
--- a/tests/unit/query_common.hpp
+++ b/tests/unit/query_common.hpp
@@ -6,7 +6,7 @@
 ///     AstStorage storage;  // Macros rely on storage being in scope.
 ///     // PROPERTY_LOOKUP and PROPERTY_PAIR macros
 ///     // rely on a DbAccessor *reference* named dba.
-///     database::SingleNode db;
+///     database::GraphDb db;
 ///     auto dba_ptr = db.Access();
 ///     auto &dba = *dba_ptr;
 ///
diff --git a/tests/unit/query_cost_estimator.cpp b/tests/unit/query_cost_estimator.cpp
index 2bdb2872e..577c48f36 100644
--- a/tests/unit/query_cost_estimator.cpp
+++ b/tests/unit/query_cost_estimator.cpp
@@ -23,7 +23,7 @@ using MiscParam = CostEstimator<database::GraphDbAccessor>::MiscParam;
  * estimation testing. */
 class QueryCostEstimator : public ::testing::Test {
  protected:
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba{db.Access()};
   storage::Label label = dba->Label("label");
   storage::Property property = dba->Property("property");
diff --git a/tests/unit/query_expression_evaluator.cpp b/tests/unit/query_expression_evaluator.cpp
index fd4fb6619..35104e71e 100644
--- a/tests/unit/query_expression_evaluator.cpp
+++ b/tests/unit/query_expression_evaluator.cpp
@@ -29,7 +29,7 @@ namespace {
 
 class ExpressionEvaluatorTest : public ::testing::Test {
  protected:
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba{db.Access()};
 
   AstStorage storage;
diff --git a/tests/unit/query_plan_accumulate_aggregate.cpp b/tests/unit/query_plan_accumulate_aggregate.cpp
index 418c130a7..a4c3dcf5b 100644
--- a/tests/unit/query_plan_accumulate_aggregate.cpp
+++ b/tests/unit/query_plan_accumulate_aggregate.cpp
@@ -27,7 +27,7 @@ TEST(QueryPlan, Accumulate) {
   // with accumulation we expect them to be [[2, 2], [2, 2]]
 
   auto check = [&](bool accumulate) {
-    database::SingleNode db;
+    database::GraphDb db;
     auto dba_ptr = db.Access();
     auto &dba = *dba_ptr;
     auto prop = dba.Property("x");
@@ -88,7 +88,7 @@ TEST(QueryPlan, AccumulateAdvance) {
   // to get correct results we need to advance the command
 
   auto check = [&](bool advance) {
-    database::SingleNode db;
+    database::GraphDb db;
     auto dba = db.Access();
     AstStorage storage;
     SymbolTable symbol_table;
@@ -150,7 +150,7 @@ std::shared_ptr<Produce> MakeAggregationProduce(
 /** Test fixture for all the aggregation ops in one return. */
 class QueryPlanAggregateOps : public ::testing::Test {
  protected:
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba_ptr{db.Access()};
   database::GraphDbAccessor &dba{*dba_ptr};
   storage::Property prop = dba.Property("prop");
@@ -290,7 +290,7 @@ TEST(QueryPlan, AggregateGroupByValues) {
   // Tests that distinct groups are aggregated properly for values of all types.
   // Also test the "remember" part of the Aggregation API as final results are
   // obtained via a property lookup of a remembered node.
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -350,7 +350,7 @@ TEST(QueryPlan, AggregateMultipleGroupBy) {
   // in this test we have 3 different properties that have different values
   // for different records and assert that we get the correct combination
   // of values in our groups
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -386,7 +386,7 @@ TEST(QueryPlan, AggregateMultipleGroupBy) {
 }
 
 TEST(QueryPlan, AggregateNoInput) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -413,7 +413,7 @@ TEST(QueryPlan, AggregateCountEdgeCases) {
   //  - 2 vertices in database, property set on one
   //  - 2 vertices in database, property set on both
 
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   auto prop = dba.Property("prop");
@@ -466,7 +466,7 @@ TEST(QueryPlan, AggregateFirstValueTypes) {
   // testing exceptions that get emitted by the first-value
   // type check
 
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -524,7 +524,7 @@ TEST(QueryPlan, AggregateTypes) {
   // does not check all combinations that can result in an exception
   // (that logic is defined and tested by TypedValue)
 
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -581,7 +581,7 @@ TEST(QueryPlan, AggregateTypes) {
 }
 
 TEST(QueryPlan, Unwind) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
diff --git a/tests/unit/query_plan_bag_semantics.cpp b/tests/unit/query_plan_bag_semantics.cpp
index eb67caacf..21d808ac4 100644
--- a/tests/unit/query_plan_bag_semantics.cpp
+++ b/tests/unit/query_plan_bag_semantics.cpp
@@ -22,7 +22,7 @@ using namespace query;
 using namespace query::plan;
 
 TEST(QueryPlan, Skip) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   AstStorage storage;
@@ -51,7 +51,7 @@ TEST(QueryPlan, Skip) {
 }
 
 TEST(QueryPlan, Limit) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   AstStorage storage;
@@ -83,7 +83,7 @@ TEST(QueryPlan, CreateLimit) {
   // CREATE (n), (m)
   // MATCH (n) CREATE (m) LIMIT 1
   // in the end we need to have 3 vertices in the db
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   dba->InsertVertex();
   dba->InsertVertex();
@@ -104,7 +104,7 @@ TEST(QueryPlan, CreateLimit) {
 }
 
 TEST(QueryPlan, OrderBy) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   AstStorage storage;
@@ -164,7 +164,7 @@ TEST(QueryPlan, OrderBy) {
 }
 
 TEST(QueryPlan, OrderByMultiple) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   AstStorage storage;
@@ -221,7 +221,7 @@ TEST(QueryPlan, OrderByMultiple) {
 }
 
 TEST(QueryPlan, OrderByExceptions) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   AstStorage storage;
diff --git a/tests/unit/query_plan_create_set_remove_delete.cpp b/tests/unit/query_plan_create_set_remove_delete.cpp
index 9e44a19a4..6bd8a31e6 100644
--- a/tests/unit/query_plan_create_set_remove_delete.cpp
+++ b/tests/unit/query_plan_create_set_remove_delete.cpp
@@ -17,7 +17,7 @@ using namespace query;
 using namespace query::plan;
 
 TEST(QueryPlan, CreateNodeWithAttributes) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -52,7 +52,7 @@ TEST(QueryPlan, CreateNodeWithAttributes) {
 
 TEST(QueryPlan, CreateReturn) {
   // test CREATE (n:Person {age: 42}) RETURN n, n.age
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -94,7 +94,7 @@ TEST(QueryPlan, CreateReturn) {
 }
 
 TEST(QueryPlan, CreateExpand) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -169,7 +169,7 @@ TEST(QueryPlan, CreateExpand) {
 }
 
 TEST(QueryPlan, MatchCreateNode) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // add three nodes we'll match and expand-create from
@@ -196,7 +196,7 @@ TEST(QueryPlan, MatchCreateNode) {
 }
 
 TEST(QueryPlan, MatchCreateExpand) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // add three nodes we'll match and expand-create from
@@ -248,7 +248,7 @@ TEST(QueryPlan, MatchCreateExpand) {
 }
 
 TEST(QueryPlan, Delete) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // make a fully-connected (one-direction, no cycles) with 4 nodes
@@ -338,7 +338,7 @@ TEST(QueryPlan, DeleteTwiceDeleteBlockingEdge) {
   // MATCH (n)-[r]-(m) [DETACH] DELETE n, r, m
 
   auto test_delete = [](bool detach) {
-    database::SingleNode db;
+    database::GraphDb db;
     auto dba = db.Access();
 
     auto v1 = dba->InsertVertex();
@@ -377,7 +377,7 @@ TEST(QueryPlan, DeleteTwiceDeleteBlockingEdge) {
 }
 
 TEST(QueryPlan, DeleteReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -417,7 +417,7 @@ TEST(QueryPlan, DeleteReturn) {
 
 TEST(QueryPlan, DeleteNull) {
   // test (simplified) WITH Null as x delete x
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -438,7 +438,7 @@ TEST(QueryPlan, DeleteAdvance) {
   // note that Neo does not fail when the deleted
   // record is not used in subsequent clauses, but
   // we are not yet compatible with that
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   dba->InsertVertex();
   dba->AdvanceCommand();
@@ -457,7 +457,7 @@ TEST(QueryPlan, DeleteAdvance) {
 }
 
 TEST(QueryPlan, SetProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -510,7 +510,7 @@ TEST(QueryPlan, SetProperty) {
 
 TEST(QueryPlan, SetProperties) {
   auto test_set_properties = [](bool update) {
-    database::SingleNode db;
+    database::GraphDb db;
     auto dba = db.Access();
 
     // graph: ({a: 0})-[:R {b:1}]->({c:2})
@@ -580,7 +580,7 @@ TEST(QueryPlan, SetProperties) {
 }
 
 TEST(QueryPlan, SetLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto label1 = dba->Label("label1");
@@ -607,7 +607,7 @@ TEST(QueryPlan, SetLabels) {
 }
 
 TEST(QueryPlan, RemoveProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -661,7 +661,7 @@ TEST(QueryPlan, RemoveProperty) {
 }
 
 TEST(QueryPlan, RemoveLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto label1 = dba->Label("label1");
@@ -693,7 +693,7 @@ TEST(QueryPlan, RemoveLabels) {
 }
 
 TEST(QueryPlan, NodeFilterSet) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Create a graph such that (v1 {prop: 42}) is connected to v2 and v3.
@@ -735,7 +735,7 @@ TEST(QueryPlan, NodeFilterSet) {
 }
 
 TEST(QueryPlan, FilterRemove) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Create a graph such that (v1 {prop: 42}) is connected to v2 and v3.
@@ -773,7 +773,7 @@ TEST(QueryPlan, FilterRemove) {
 }
 
 TEST(QueryPlan, SetRemove) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v = dba->InsertVertex();
   auto label1 = dba->Label("label1");
@@ -803,7 +803,7 @@ TEST(QueryPlan, Merge) {
   //  - merge_match branch looks for an expansion (any direction)
   //    and sets some property (for result validation)
   //  - merge_create branch just sets some other property
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   auto v1 = dba.InsertVertex();
@@ -850,7 +850,7 @@ TEST(QueryPlan, Merge) {
 TEST(QueryPlan, MergeNoInput) {
   // merge with no input, creates a single node
 
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -869,7 +869,7 @@ TEST(QueryPlan, MergeNoInput) {
 
 TEST(QueryPlan, SetPropertyOnNull) {
   // SET (Null).prop = 42
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   AstStorage storage;
@@ -885,7 +885,7 @@ TEST(QueryPlan, SetPropertyOnNull) {
 
 TEST(QueryPlan, SetPropertiesOnNull) {
   // OPTIONAL MATCH (n) SET n = n
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -902,7 +902,7 @@ TEST(QueryPlan, SetPropertiesOnNull) {
 
 TEST(QueryPlan, SetLabelsOnNull) {
   // OPTIONAL MATCH (n) SET n :label
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto label = dba->Label("label");
   AstStorage storage;
@@ -920,7 +920,7 @@ TEST(QueryPlan, SetLabelsOnNull) {
 
 TEST(QueryPlan, RemovePropertyOnNull) {
   // REMOVE (Null).prop
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   AstStorage storage;
@@ -935,7 +935,7 @@ TEST(QueryPlan, RemovePropertyOnNull) {
 
 TEST(QueryPlan, RemoveLabelsOnNull) {
   // OPTIONAL MATCH (n) REMOVE n :label
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto label = dba->Label("label");
   AstStorage storage;
@@ -953,7 +953,7 @@ TEST(QueryPlan, RemoveLabelsOnNull) {
 
 TEST(QueryPlan, CreateIndex) {
   // CREATE INDEX ON :Label(property)
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto label = dba->Label("label");
   auto property = dba->Property("property");
@@ -965,7 +965,7 @@ TEST(QueryPlan, CreateIndex) {
 }
 
 TEST(QueryPlan, DeleteSetProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Add a single vertex.
@@ -989,7 +989,7 @@ TEST(QueryPlan, DeleteSetProperty) {
 }
 
 TEST(QueryPlan, DeleteSetPropertiesFromMap) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Add a single vertex.
@@ -1021,7 +1021,7 @@ TEST(QueryPlan, DeleteSetPropertiesFromMap) {
 }
 
 TEST(QueryPlan, DeleteSetPropertiesFromVertex) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Add a single vertex.
@@ -1053,7 +1053,7 @@ TEST(QueryPlan, DeleteSetPropertiesFromVertex) {
 }
 
 TEST(QueryPlan, DeleteRemoveLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Add a single vertex.
   dba->InsertVertex();
@@ -1073,7 +1073,7 @@ TEST(QueryPlan, DeleteRemoveLabels) {
 }
 
 TEST(QueryPlan, DeleteRemoveProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   // Add a single vertex.
diff --git a/tests/unit/query_plan_edge_cases.cpp b/tests/unit/query_plan_edge_cases.cpp
index 7a2a923be..27f9f0ce4 100644
--- a/tests/unit/query_plan_edge_cases.cpp
+++ b/tests/unit/query_plan_edge_cases.cpp
@@ -16,7 +16,7 @@ DECLARE_bool(query_cost_planner);
 
 class QueryExecution : public testing::Test {
  protected:
-  std::experimental::optional<database::SingleNode> db_;
+  std::experimental::optional<database::GraphDb> db_;
   std::unique_ptr<database::GraphDbAccessor> dba_;
 
   void SetUp() {
diff --git a/tests/unit/query_plan_match_filter_return.cpp b/tests/unit/query_plan_match_filter_return.cpp
index 455b96b92..2c8f091cc 100644
--- a/tests/unit/query_plan_match_filter_return.cpp
+++ b/tests/unit/query_plan_match_filter_return.cpp
@@ -26,7 +26,7 @@ using namespace query::plan;
 
 class MatchReturnFixture : public testing::Test {
  protected:
-  database::SingleNode db_;
+  database::GraphDb db_;
   std::unique_ptr<database::GraphDbAccessor> dba_{db_.Access()};
   AstStorage storage;
   SymbolTable symbol_table;
@@ -90,7 +90,7 @@ TEST_F(MatchReturnFixture, MatchReturnPath) {
 }
 
 TEST(QueryPlan, MatchReturnCartesian) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   dba->InsertVertex().add_label(dba->Label("l1"));
@@ -123,7 +123,7 @@ TEST(QueryPlan, MatchReturnCartesian) {
 }
 
 TEST(QueryPlan, StandaloneReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // add a few nodes to the database
@@ -145,7 +145,7 @@ TEST(QueryPlan, StandaloneReturn) {
 }
 
 TEST(QueryPlan, NodeFilterLabelsAndProperties) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -202,7 +202,7 @@ TEST(QueryPlan, NodeFilterLabelsAndProperties) {
 }
 
 TEST(QueryPlan, NodeFilterMultipleLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // add a few nodes to the database
@@ -252,7 +252,7 @@ TEST(QueryPlan, NodeFilterMultipleLabels) {
 }
 
 TEST(QueryPlan, Cartesian) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto add_vertex = [&dba](std::string label) {
@@ -297,7 +297,7 @@ TEST(QueryPlan, Cartesian) {
 }
 
 TEST(QueryPlan, CartesianEmptySet) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   AstStorage storage;
@@ -326,7 +326,7 @@ TEST(QueryPlan, CartesianEmptySet) {
 }
 
 TEST(QueryPlan, CartesianThreeWay) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto add_vertex = [&dba](std::string label) {
     auto vertex = dba->InsertVertex();
@@ -386,7 +386,7 @@ TEST(QueryPlan, CartesianThreeWay) {
 
 class ExpandFixture : public testing::Test {
  protected:
-  database::SingleNode db_;
+  database::GraphDb db_;
   std::unique_ptr<database::GraphDbAccessor> dba_{db_.Access()};
   AstStorage storage;
   SymbolTable symbol_table;
@@ -483,7 +483,7 @@ class QueryPlanExpandVariable : public testing::Test {
   // a lot below in test declaration
   using map_int = std::unordered_map<int, int>;
 
-  database::SingleNode db_;
+  database::GraphDb db_;
   std::unique_ptr<database::GraphDbAccessor> dba_{db_.Access()};
   // labels for layers in the double chain
   std::vector<storage::Label> labels;
@@ -839,7 +839,7 @@ class QueryPlanExpandWeightedShortestPath : public testing::Test {
  protected:
   // style-guide non-conformant name due to PROPERTY_PAIR and
   // PROPERTY_LOOKUP macro requirements
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba_ptr{db.Access()};
   database::GraphDbAccessor &dba{*dba_ptr};
   std::pair<std::string, storage::Property> prop = PROPERTY_PAIR("property");
@@ -1192,7 +1192,7 @@ TEST_F(QueryPlanExpandWeightedShortestPath, Exceptions) {
 }
 
 TEST(QueryPlan, ExpandOptional) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   AstStorage storage;
@@ -1252,7 +1252,7 @@ TEST(QueryPlan, ExpandOptional) {
 }
 
 TEST(QueryPlan, OptionalMatchEmptyDB) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   AstStorage storage;
@@ -1274,7 +1274,7 @@ TEST(QueryPlan, OptionalMatchEmptyDB) {
 }
 
 TEST(QueryPlan, OptionalMatchEmptyDBExpandFromNode) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -1302,7 +1302,7 @@ TEST(QueryPlan, OptionalMatchEmptyDBExpandFromNode) {
 }
 
 TEST(QueryPlan, OptionalMatchThenExpandToMissingNode) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Make a graph with 2 connected, unlabeled nodes.
   auto v1 = dba->InsertVertex();
@@ -1351,7 +1351,7 @@ TEST(QueryPlan, OptionalMatchThenExpandToMissingNode) {
 }
 
 TEST(QueryPlan, ExpandExistingNode) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // make a graph (v1)->(v2) that
@@ -1395,7 +1395,7 @@ TEST(QueryPlan, ExpandExistingNode) {
 TEST(QueryPlan, ExpandBothCycleEdgeCase) {
   // we're testing that expanding on BOTH
   // does only one expansion for a cycle
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto v = dba->InsertVertex();
@@ -1413,7 +1413,7 @@ TEST(QueryPlan, ExpandBothCycleEdgeCase) {
 }
 
 TEST(QueryPlan, EdgeFilter) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -1483,7 +1483,7 @@ TEST(QueryPlan, EdgeFilter) {
 }
 
 TEST(QueryPlan, EdgeFilterMultipleTypes) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto v1 = dba->InsertVertex();
@@ -1518,7 +1518,7 @@ TEST(QueryPlan, EdgeFilterMultipleTypes) {
 }
 
 TEST(QueryPlan, Filter) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
 
@@ -1548,7 +1548,7 @@ TEST(QueryPlan, Filter) {
 }
 
 TEST(QueryPlan, ExpandUniquenessFilter) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   // make a graph that has (v1)->(v2) and a recursive edge (v1)->(v1)
@@ -1596,7 +1596,7 @@ TEST(QueryPlan, Distinct) {
   // test queries like
   // UNWIND [1, 2, 3, 3] AS x RETURN DISTINCT x
 
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   AstStorage storage;
   SymbolTable symbol_table;
@@ -1638,7 +1638,7 @@ TEST(QueryPlan, Distinct) {
 }
 
 TEST(QueryPlan, ScanAllByLabel) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Add a vertex with a label and one without.
   auto label = dba->Label("label");
@@ -1665,7 +1665,7 @@ TEST(QueryPlan, ScanAllByLabel) {
 }
 
 TEST(QueryPlan, ScanAllByLabelProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   // Add 5 vertices with same label, but with different property values.
   auto label = db.Access()->Label("label");
   auto prop = db.Access()->Property("prop");
@@ -1735,7 +1735,7 @@ TEST(QueryPlan, ScanAllByLabelProperty) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyEqualityNoError) {
-  database::SingleNode db;
+  database::GraphDb db;
   // Add 2 vertices with same label, but with property values that cannot be
   // compared. On the other hand, equality works fine.
   auto label = db.Access()->Label("label");
@@ -1774,7 +1774,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyEqualityNoError) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyValueError) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto label = db.Access()->Label("label");
   auto prop = db.Access()->Property("prop");
   {
@@ -1802,7 +1802,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyValueError) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyRangeError) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto label = db.Access()->Label("label");
   auto prop = db.Access()->Property("prop");
   {
@@ -1852,7 +1852,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyRangeError) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyEqualNull) {
-  database::SingleNode db;
+  database::GraphDb db;
   // Add 2 vertices with the same label, but one has a property value while
   // the other does not. Checking if the value is equal to null, should
   // yield no results.
@@ -1885,7 +1885,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyEqualNull) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyRangeNull) {
-  database::SingleNode db;
+  database::GraphDb db;
   // Add 2 vertices with the same label, but one has a property value while
   // the other does not. Checking if the value is between nulls, should
   // yield no results.
@@ -1920,7 +1920,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyRangeNull) {
 }
 
 TEST(QueryPlan, ScanAllByLabelPropertyNoValueInIndexContinuation) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto label = db.Access()->Label("label");
   auto prop = db.Access()->Property("prop");
   {
@@ -1952,7 +1952,7 @@ TEST(QueryPlan, ScanAllByLabelPropertyNoValueInIndexContinuation) {
 }
 
 TEST(QueryPlan, ScanAllEqualsScanAllByLabelProperty) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto label = db.Access()->Label("label");
   auto prop = db.Access()->Property("prop");
 
diff --git a/tests/unit/query_semantic.cpp b/tests/unit/query_semantic.cpp
index e7c6bd13e..85ce9ef70 100644
--- a/tests/unit/query_semantic.cpp
+++ b/tests/unit/query_semantic.cpp
@@ -15,7 +15,7 @@ using namespace query;
 
 class TestSymbolGenerator : public ::testing::Test {
  protected:
-  database::SingleNode db;
+  database::GraphDb db;
   std::unique_ptr<database::GraphDbAccessor> dba_ptr{db.Access()};
   database::GraphDbAccessor &dba{*dba_ptr};
   SymbolTable symbol_table;
diff --git a/tests/unit/query_variable_start_planner.cpp b/tests/unit/query_variable_start_planner.cpp
index 525a52ba1..187cd1092 100644
--- a/tests/unit/query_variable_start_planner.cpp
+++ b/tests/unit/query_variable_start_planner.cpp
@@ -83,7 +83,7 @@ void CheckPlansProduce(
 }
 
 TEST(TestVariableStartPlanner, MatchReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Make a graph (v1) -[:r]-> (v2)
   auto v1 = dba->InsertVertex();
@@ -103,7 +103,7 @@ TEST(TestVariableStartPlanner, MatchReturn) {
 }
 
 TEST(TestVariableStartPlanner, MatchTripletPatternReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Make a graph (v1) -[:r]-> (v2) -[:r]-> (v3)
   auto v1 = dba->InsertVertex();
@@ -139,7 +139,7 @@ TEST(TestVariableStartPlanner, MatchTripletPatternReturn) {
 }
 
 TEST(TestVariableStartPlanner, MatchOptionalMatchReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Make a graph (v1) -[:r]-> (v2) -[:r]-> (v3)
   auto v1 = dba->InsertVertex();
@@ -165,7 +165,7 @@ TEST(TestVariableStartPlanner, MatchOptionalMatchReturn) {
 }
 
 TEST(TestVariableStartPlanner, MatchOptionalMatchMergeReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Graph (v1) -[:r]-> (v2)
   auto v1 = dba->InsertVertex();
@@ -190,7 +190,7 @@ TEST(TestVariableStartPlanner, MatchOptionalMatchMergeReturn) {
 }
 
 TEST(TestVariableStartPlanner, MatchWithMatchReturn) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Graph (v1) -[:r]-> (v2)
   auto v1 = dba->InsertVertex();
@@ -213,7 +213,7 @@ TEST(TestVariableStartPlanner, MatchWithMatchReturn) {
 }
 
 TEST(TestVariableStartPlanner, MatchVariableExpand) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   // Graph (v1) -[:r1]-> (v2) -[:r2]-> (v3)
   auto v1 = dba->InsertVertex();
@@ -236,7 +236,7 @@ TEST(TestVariableStartPlanner, MatchVariableExpand) {
 }
 
 TEST(TestVariableStartPlanner, MatchVariableExpandReferenceNode) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   auto id = dba.Property("id");
@@ -264,7 +264,7 @@ TEST(TestVariableStartPlanner, MatchVariableExpandReferenceNode) {
 }
 
 TEST(TestVariableStartPlanner, MatchVariableExpandBoth) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto id = dba->Property("id");
   // Graph (v1 {id:1}) -[:r1]-> (v2) -[:r2]-> (v3)
@@ -290,7 +290,7 @@ TEST(TestVariableStartPlanner, MatchVariableExpandBoth) {
 }
 
 TEST(TestVariableStartPlanner, MatchBfs) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba_ptr = db.Access();
   auto &dba = *dba_ptr;
   auto id = dba.Property("id");
diff --git a/tests/unit/record_edge_vertex_accessor.cpp b/tests/unit/record_edge_vertex_accessor.cpp
index e1b52457a..525a816ec 100644
--- a/tests/unit/record_edge_vertex_accessor.cpp
+++ b/tests/unit/record_edge_vertex_accessor.cpp
@@ -13,7 +13,7 @@
 #include "storage/single_node/vertex_accessor.hpp"
 
 TEST(RecordAccessor, Properties) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto vertex = dba->InsertVertex();
@@ -35,7 +35,7 @@ TEST(RecordAccessor, Properties) {
 }
 
 TEST(RecordAccessor, DbAccessor) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto vertex = dba->InsertVertex();
@@ -46,7 +46,7 @@ TEST(RecordAccessor, DbAccessor) {
 }
 
 TEST(RecordAccessor, RecordEquality) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto v1 = dba->InsertVertex();
@@ -61,7 +61,7 @@ TEST(RecordAccessor, RecordEquality) {
 }
 
 TEST(RecordAccessor, GlobalToLocalAddressConversion) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
 
   auto v1 = dba->InsertVertex();
@@ -73,7 +73,7 @@ TEST(RecordAccessor, GlobalToLocalAddressConversion) {
 }
 
 TEST(RecordAccessor, SwitchOldAndSwitchNewMemberFunctionTest) {
-  database::SingleNode db;
+  database::GraphDb db;
 
   // test both Switches work on new record
   {
@@ -109,7 +109,7 @@ TEST(RecordAccessor, SwitchOldAndSwitchNewMemberFunctionTest) {
 }
 
 TEST(RecordAccessor, Reconstruct) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto label = db.Access()->Label("label");
 
   {
@@ -143,7 +143,7 @@ TEST(RecordAccessor, Reconstruct) {
 }
 
 TEST(RecordAccessor, VertexLabels) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto &labels = v1.labels();
@@ -184,7 +184,7 @@ TEST(RecordAccessor, VertexLabels) {
 }
 
 TEST(RecordAccessor, EdgeType) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto v2 = dba->InsertVertex();
@@ -198,7 +198,7 @@ TEST(RecordAccessor, EdgeType) {
 }
 
 TEST(RecordAccessor, EdgeIsCycle) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto v2 = dba->InsertVertex();
@@ -211,7 +211,7 @@ TEST(RecordAccessor, EdgeIsCycle) {
 }
 
 TEST(RecordAccessor, VertexEdgeConnections) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto v2 = dba->InsertVertex();
@@ -243,7 +243,7 @@ TEST(RecordAccessor, VertexEdgeConnections) {
   }
 
 TEST(RecordAccessor, VertexEdgeConnectionsWithExistingVertex) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto v2 = dba->InsertVertex();
@@ -278,7 +278,7 @@ TEST(RecordAccessor, VertexEdgeConnectionsWithExistingVertex) {
 }
 
 TEST(RecordAccessor, VertexEdgeConnectionsWithEdgeType) {
-  database::SingleNode db;
+  database::GraphDb db;
   auto dba = db.Access();
   auto v1 = dba->InsertVertex();
   auto v2 = dba->InsertVertex();
diff --git a/tests/unit/state_delta.cpp b/tests/unit/state_delta.cpp
index 17017b5cc..764193508 100644
--- a/tests/unit/state_delta.cpp
+++ b/tests/unit/state_delta.cpp
@@ -5,7 +5,7 @@
 #include "durability/single_node/state_delta.hpp"
 
 TEST(StateDelta, CreateVertex) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   {
@@ -24,7 +24,7 @@ TEST(StateDelta, CreateVertex) {
 }
 
 TEST(StateDelta, RemoveVertex) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   {
@@ -47,7 +47,7 @@ TEST(StateDelta, RemoveVertex) {
 }
 
 TEST(StateDelta, CreateEdge) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   auto gid1 = generator.Next();
@@ -74,7 +74,7 @@ TEST(StateDelta, CreateEdge) {
 }
 
 TEST(StateDelta, RemoveEdge) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   auto gid1 = generator.Next();
@@ -100,7 +100,7 @@ TEST(StateDelta, RemoveEdge) {
 }
 
 TEST(StateDelta, AddLabel) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   {
@@ -126,7 +126,7 @@ TEST(StateDelta, AddLabel) {
 }
 
 TEST(StateDelta, RemoveLabel) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   {
@@ -152,7 +152,7 @@ TEST(StateDelta, RemoveLabel) {
 }
 
 TEST(StateDelta, SetPropertyVertex) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   {
@@ -178,7 +178,7 @@ TEST(StateDelta, SetPropertyVertex) {
 }
 
 TEST(StateDelta, SetPropertyEdge) {
-  database::SingleNode db;
+  database::GraphDb db;
   gid::Generator generator(0);
   auto gid0 = generator.Next();
   auto gid1 = generator.Next();
diff --git a/tests/unit/transaction_engine_single_node.cpp b/tests/unit/transaction_engine_single_node.cpp
index 67d8ce2b7..c11f03555 100644
--- a/tests/unit/transaction_engine_single_node.cpp
+++ b/tests/unit/transaction_engine_single_node.cpp
@@ -4,13 +4,13 @@
 #include <vector>
 
 #include "data_structures/concurrent/skiplist.hpp"
-#include "transactions/single_node/engine_single_node.hpp"
+#include "transactions/single_node/engine.hpp"
 #include "transactions/transaction.hpp"
 
 using namespace tx;
 
 TEST(Engine, GcSnapshot) {
-  EngineSingleNode engine;
+  Engine engine;
   ASSERT_EQ(engine.GlobalGcSnapshot(), Snapshot({1}));
 
   std::vector<Transaction *> transactions;
@@ -38,7 +38,7 @@ TEST(Engine, GcSnapshot) {
 }
 
 TEST(Engine, Advance) {
-  EngineSingleNode engine;
+  Engine engine;
 
   auto t0 = engine.Begin();
   auto t1 = engine.Begin();
@@ -51,7 +51,7 @@ TEST(Engine, Advance) {
 }
 
 TEST(Engine, ConcurrentBegin) {
-  EngineSingleNode engine;
+  Engine engine;
   std::vector<std::thread> threads;
   SkipList<TransactionId> tx_ids;
   for (int i = 0; i < 10; ++i) {
@@ -67,7 +67,7 @@ TEST(Engine, ConcurrentBegin) {
 }
 
 TEST(Engine, RunningTransaction) {
-  EngineSingleNode engine;
+  Engine engine;
   auto t0 = engine.Begin();
   auto t1 = engine.Begin();
   EXPECT_EQ(t0, engine.RunningTransaction(t0->id_));
@@ -76,7 +76,7 @@ TEST(Engine, RunningTransaction) {
 }
 
 TEST(Engine, EnsureTxIdGreater) {
-  EngineSingleNode engine;
+  Engine engine;
   ASSERT_LE(engine.Begin()->id_, 40);
   engine.EnsureNextIdGreater(42);
   EXPECT_EQ(engine.Begin()->id_, 43);
diff --git a/tests/unit/typed_value.cpp b/tests/unit/typed_value.cpp
index c664dc051..87b714fb8 100644
--- a/tests/unit/typed_value.cpp
+++ b/tests/unit/typed_value.cpp
@@ -18,7 +18,7 @@ using query::TypedValueException;
 class AllTypesFixture : public testing::Test {
  protected:
   std::vector<TypedValue> values_;
-  database::SingleNode db_;
+  database::GraphDb db_;
   std::unique_ptr<database::GraphDbAccessor> dba_{db_.Access()};
 
   void SetUp() override {
diff --git a/tools/tests/mg_recovery_check.cpp b/tools/tests/mg_recovery_check.cpp
index e11c22711..24e51765c 100644
--- a/tools/tests/mg_recovery_check.cpp
+++ b/tools/tests/mg_recovery_check.cpp
@@ -24,13 +24,13 @@ class RecoveryTest : public ::testing::Test {
     durability::RecoveryData recovery_data;
     durability::RecoverOnlySnapshot(durability_dir, &db_, &recovery_data,
                                     std::experimental::nullopt, 0);
-    database::SingleNodeRecoveryTransanctions recovery_transactions(&db_);
+    durability::RecoveryTransactions recovery_transactions(&db_);
     durability::RecoverWal(durability_dir, &db_, &recovery_data,
                                &recovery_transactions);
     durability::RecoverIndexes(&db_, recovery_data.indexes);
   }
 
-  database::SingleNode db_;
+  database::GraphDb db_;
 };
 
 TEST_F(RecoveryTest, TestVerticesRecovered) {