From a44d9a0facb7f1f7f01dd8408c4875db6049cc55 Mon Sep 17 00:00:00 2001
From: Teon Banek <teon.banek@memgraph.io>
Date: Mon, 26 Feb 2018 11:08:39 +0100
Subject: [PATCH] Always plan Synchronize if the plan needs it

Reviewers: florijan, msantl

Reviewed By: florijan

Subscribers: pullbot

Differential Revision: https://phabricator.memgraph.io/D1241
---
 src/query/plan/distributed.cpp |  6 +++---
 tests/unit/query_planner.cpp   | 28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/query/plan/distributed.cpp b/src/query/plan/distributed.cpp
index db36d0f5c..aeaca0e9a 100644
--- a/src/query/plan/distributed.cpp
+++ b/src/query/plan/distributed.cpp
@@ -771,9 +771,9 @@ DistributedPlan MakeDistributedPlan(const LogicalOperator &original_plan,
           worker_plan, pull_id,
           worker_plan->OutputSymbols(distributed_plan.symbol_table));
     }
-  } else if (distributed_plan.worker_plans.empty() &&
-             planner.NeedsSynchronize()) {
-    // If the plan performs writes, we still need to Synchronize.
+  } else if (planner.NeedsSynchronize()) {
+    // If the plan performs writes on master, we still need to Synchronize, even
+    // though we don't split the plan.
     distributed_plan.master_plan = std::make_unique<Synchronize>(
         std::move(distributed_plan.master_plan), nullptr, false);
   }
diff --git a/tests/unit/query_planner.cpp b/tests/unit/query_planner.cpp
index ed75fabfe..62eba6d69 100644
--- a/tests/unit/query_planner.cpp
+++ b/tests/unit/query_planner.cpp
@@ -2204,4 +2204,32 @@ TYPED_TEST(TestPlanner, DistributedMatchCreateReturn) {
       MakeCheckers(ExpectScanAll(), ExpectCreateNode()));
   CheckDistributedPlan(planner.plan(), symbol_table, expected);
 }
+
+TYPED_TEST(TestPlanner, DistributedCartesianCreate) {
+  // Test MATCH (a), (b) CREATE (a)-[e:r]->(b)
+  AstTreeStorage storage;
+  database::Master db;
+  database::GraphDbAccessor dba(db);
+  auto relationship = dba.EdgeType("r");
+  auto *node_a = NODE("a");
+  auto *node_b = NODE("b");
+  QUERY(SINGLE_QUERY(
+      MATCH(PATTERN(node_a), PATTERN(node_b)),
+      CREATE(PATTERN(NODE("a"), EDGE("e", Direction::OUT, {relationship}),
+                     NODE("b")))));
+  auto symbol_table = MakeSymbolTable(*storage.query());
+  auto left_cart =
+      MakeCheckers(ExpectScanAll(),
+                   ExpectPullRemote({symbol_table.at(*node_a->identifier_)}));
+  auto right_cart =
+      MakeCheckers(ExpectScanAll(),
+                   ExpectPullRemote({symbol_table.at(*node_b->identifier_)}));
+  auto expected = ExpectDistributed(
+      MakeCheckers(ExpectCartesian(std::move(left_cart), std::move(right_cart)),
+                   ExpectCreateExpand(), ExpectSynchronize(false)),
+      MakeCheckers(ExpectScanAll()), MakeCheckers(ExpectScanAll()));
+  auto planner = MakePlanner<TypeParam>(db, storage, symbol_table);
+  CheckDistributedPlan(planner.plan(), symbol_table, expected);
+}
+
 }  // namespace