Auto generate vertex/edge ids

Reviewers: buda

Reviewed By: buda

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1406

src/database/graph_db_accessor.cpp

@@ -15,6 +15,18 @@
 #include "utils/atomic.hpp"
 #include "utils/on_scope_exit.hpp"
 
+// Autogenerate property with Vertex ID
+DEFINE_bool(
+    generate_vertex_ids, false,
+    "If enabled database will automatically generate Ids as properties of "
+    "vertices, which can be accessed using the `Id` cypher function.");
+
+// Autogenerate property with Edge ID
+DEFINE_bool(
+    generate_edge_ids, false,
+    "If enabled database will automatically generate Ids as properties of "
+    "edges, which can be accessed using the `Id` cypher function.");
+
 namespace database {
 
 GraphDbAccessor::GraphDbAccessor(GraphDb &db)
@@ -65,7 +77,7 @@ VertexAccessor GraphDbAccessor::InsertVertex(
     std::experimental::optional<gid::Gid> requested_gid) {
   DCHECK(!commited_ && !aborted_) << "Accessor committed or aborted";
 
-  auto gid = db_.storage().vertex_generator_.Next(requested_gid);
+  int64_t gid = db_.storage().vertex_generator_.Next(requested_gid);
   auto vertex_vlist = new mvcc::VersionList<Vertex>(transaction_, gid);
 
   bool success =
@@ -74,7 +86,10 @@ VertexAccessor GraphDbAccessor::InsertVertex(
                  << gid;
   wal().Emplace(
       database::StateDelta::CreateVertex(transaction_.id_, vertex_vlist->gid_));
-  return VertexAccessor(vertex_vlist, *this);
+  auto va = VertexAccessor(vertex_vlist, *this);
+  if (FLAGS_generate_vertex_ids)
+    va.PropsSet(Property(PropertyValueStore::IdPropertyName), gid);
+  return va;
 }
 
 VertexAccessor GraphDbAccessor::InsertVertexIntoRemote(
@@ -391,16 +406,9 @@ EdgeAccessor GraphDbAccessor::InsertEdge(
 
   Vertex *from_updated;
   if (from.is_local()) {
-    auto gid = db_.storage().edge_generator_.Next(requested_gid);
-    edge_address = new mvcc::VersionList<Edge>(
-        transaction_, gid, from.address(), to.address(), edge_type);
-    // We need to insert edge_address to edges_ before calling update since
-    // update can throw and edge_vlist will not be garbage collected if it is
-    // not in edges_ skiplist.
-    bool success =
-        db_.storage().edges_.access().insert(gid, edge_address.local()).second;
-    CHECK(success) << "Attempting to insert an edge with an existing GID: "
-                   << gid;
+    auto edge_accessor =
+        InsertOnlyEdge(from.address(), to.address(), edge_type, requested_gid);
+    edge_address = edge_accessor.address(),
 
     from.SwitchNew();
     from_updated = &from.update();
@@ -409,7 +417,7 @@ EdgeAccessor GraphDbAccessor::InsertEdge(
     // `CREATE_EDGE`, but always have it split into 3 parts (edge insertion,
     // in/out modification).
     wal().Emplace(database::StateDelta::CreateEdge(
-        transaction_.id_, gid, from.gid(), to.gid(), edge_type,
+        transaction_.id_, edge_accessor.gid(), from.gid(), to.gid(), edge_type,
         EdgeTypeName(edge_type)));
 
   } else {
@@ -467,7 +475,7 @@ EdgeAccessor GraphDbAccessor::InsertOnlyEdge(
     std::experimental::optional<gid::Gid> requested_gid) {
   CHECK(from.is_local())
       << "`from` address should be local when calling InsertOnlyEdge";
-  auto gid = db_.storage().edge_generator_.Next(requested_gid);
+  int64_t gid = db_.storage().edge_generator_.Next(requested_gid);
   auto edge_vlist =
       new mvcc::VersionList<Edge>(transaction_, gid, from, to, edge_type);
   // We need to insert edge_vlist to edges_ before calling update since update
@@ -476,7 +484,10 @@ EdgeAccessor GraphDbAccessor::InsertOnlyEdge(
   bool success = db_.storage().edges_.access().insert(gid, edge_vlist).second;
   CHECK(success) << "Attempting to insert an edge with an existing GID: "
                  << gid;
-  return EdgeAccessor(edge_vlist, *this, from, to, edge_type);
+  auto ea = EdgeAccessor(edge_vlist, *this, from, to, edge_type);
+  if (FLAGS_generate_edge_ids)
+    ea.PropsSet(Property(PropertyValueStore::IdPropertyName), gid);
+  return ea;
 }
 
 int64_t GraphDbAccessor::EdgesCount() const {

src/query/interpret/awesome_memgraph_functions.cpp

@@ -624,16 +624,32 @@ TypedValue WorkerId(const std::vector<TypedValue> &args,
 }
 
 TypedValue Id(const std::vector<TypedValue> &args,
-              database::GraphDbAccessor &) {
+              database::GraphDbAccessor &dba) {
   if (args.size() != 1U) {
     throw QueryRuntimeException("Id takes one argument");
   }
   auto &arg = args[0];
   switch (arg.type()) {
-    case TypedValue::Type::Vertex:
-      return static_cast<int64_t>(arg.ValueVertex().gid());
-    case TypedValue::Type::Edge:
-      return static_cast<int64_t>(arg.ValueEdge().gid());
+    case TypedValue::Type::Vertex: {
+      auto id = arg.ValueVertex().PropsAt(
+          dba.Property(PropertyValueStore::IdPropertyName));
+      if (id.IsNull()) {
+        throw QueryRuntimeException(
+            "Ids are not set on vertices, have a look at flags to "
+            "automatically generate them.");
+      }
+      return id.Value<int64_t>();
+    }
+    case TypedValue::Type::Edge: {
+      auto id = arg.ValueEdge().PropsAt(
+          dba.Property(PropertyValueStore::IdPropertyName));
+      if (id.IsNull()) {
+        throw QueryRuntimeException(
+            "Ids are not set on edges, have a look at flags to "
+            "automatically generate them.");
+      }
+      return id.Value<int64_t>();
+    }
     default:
       throw QueryRuntimeException("Id argument must be a vertex or edge");
   }

src/storage/property_value_store.hpp

@@ -33,6 +33,10 @@ class PropertyValueStore {
   using Location = storage::Location;
 
  public:
+  // Property name which will be used to store vertex/edge ids inside property
+  // value store
+  static constexpr char IdPropertyName[] = "__id__";
+
   PropertyValueStore() = default;
 
   PropertyValueStore(const PropertyValueStore &old) {

tests/unit/query_expression_evaluator.cpp

@@ -4,6 +4,7 @@
 #include <unordered_map>
 #include <vector>
 
+#include "gflags/gflags.h"
 #include "gmock/gmock.h"
 #include "gtest/gtest.h"
 
@@ -24,6 +25,9 @@ using query::test_common::ToList;
 using testing::ElementsAre;
 using testing::UnorderedElementsAre;
 
+DECLARE_bool(generate_vertex_ids);
+DECLARE_bool(generate_edge_ids);
+
 namespace {
 
 struct NoContextExpressionEvaluator {
@@ -1364,19 +1368,43 @@ TEST(ExpressionEvaluator, FunctionIndexInfo) {
   }
 }
 
-TEST(ExpressionEvaluator, FunctionUid) {
+TEST(ExpressionEvaluator, FunctionIdNoGeneration) {
   database::SingleNode db;
   EXPECT_THROW(EvaluateFunction("ID", {}, db), QueryRuntimeException);
   database::GraphDbAccessor dba(db);
 
+  auto va = dba.InsertVertex();
+  auto ea = dba.InsertEdge(va, va, dba.EdgeType("edge"));
+  // Unable to get id if they are not set
+  EXPECT_THROW(EvaluateFunction("ID", {va}, db), QueryRuntimeException);
+  EXPECT_THROW(EvaluateFunction("ID", {ea}, db), QueryRuntimeException);
+}
+
+TEST(ExpressionEvaluator, FunctionIdGenerateVertexIds) {
+  FLAGS_generate_vertex_ids = true;
+  database::SingleNode db;
+  database::GraphDbAccessor dba(db);
   auto va = dba.InsertVertex();
   auto ea = dba.InsertEdge(va, va, dba.EdgeType("edge"));
   EXPECT_EQ(EvaluateFunction("ID", {va}, db).Value<int64_t>(), 0);
-  EXPECT_EQ(EvaluateFunction("ID", {ea}, db).Value<int64_t>(), 0);
+  EXPECT_THROW(EvaluateFunction("ID", {ea}, db), QueryRuntimeException);
 
   auto vb = dba.InsertVertex();
-  auto eb = dba.InsertEdge(vb, vb, dba.EdgeType("edge"));
   EXPECT_EQ(EvaluateFunction("ID", {vb}, db).Value<int64_t>(), 1024);
+  FLAGS_generate_vertex_ids = false;
+}
+
+TEST(ExpressionEvaluator, FunctionIdGenerateEdgeIds) {
+  FLAGS_generate_edge_ids = true;
+  database::SingleNode db;
+  database::GraphDbAccessor dba(db);
+  auto va = dba.InsertVertex();
+  auto ea = dba.InsertEdge(va, va, dba.EdgeType("edge"));
+  EXPECT_THROW(EvaluateFunction("ID", {va}, db), QueryRuntimeException);
+  EXPECT_EQ(EvaluateFunction("ID", {ea}, db).Value<int64_t>(), 0);
+
+  auto eb = dba.InsertEdge(va, va, dba.EdgeType("edge"));
   EXPECT_EQ(EvaluateFunction("ID", {eb}, db).Value<int64_t>(), 1024);
+  FLAGS_generate_edge_ids = false;
 }
 }  // namespace