diff options
| -rw-r--r-- | src/backend/optimizer/util/clauses.c | 16 | ||||
| -rw-r--r-- | src/test/regress/expected/select_parallel.out | 26 | ||||
| -rw-r--r-- | src/test/regress/sql/select_parallel.sql | 6 |
3 files changed, 47 insertions, 1 deletions
diff --git a/src/backend/optimizer/util/clauses.c b/src/backend/optimizer/util/clauses.c index a04ad6e99e6..ee6f4cdf4da 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -1190,13 +1190,27 @@ max_parallel_hazard_walker(Node *node, max_parallel_hazard_context *context) return true; } - if (IsA(node, NextValueExpr)) + else if (IsA(node, NextValueExpr)) { if (max_parallel_hazard_test(PROPARALLEL_UNSAFE, context)) return true; } /* + * Treat window functions as parallel-restricted because we aren't sure + * whether the input row ordering is fully deterministic, and the output + * of window functions might vary across workers if not. (In some cases, + * like where the window frame orders by a primary key, we could relax + * this restriction. But it doesn't currently seem worth expending extra + * effort to do so.) + */ + else if (IsA(node, WindowFunc)) + { + if (max_parallel_hazard_test(PROPARALLEL_RESTRICTED, context)) + return true; + } + + /* * As a notational convenience for callers, look through RestrictInfo. */ else if (IsA(node, RestrictInfo)) diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out index f1b8cd43376..13cdd3d5cca 100644 --- a/src/test/regress/expected/select_parallel.out +++ b/src/test/regress/expected/select_parallel.out @@ -958,6 +958,32 @@ select count(*) from tenk1; reset force_parallel_mode; reset role; +-- Window function calculation can't be pushed to workers. +explain (costs off, verbose) + select count(*) from tenk1 a where (unique1, two) in + (select unique1, row_number() over() from tenk1 b); + QUERY PLAN +---------------------------------------------------------------------------------------------- + Aggregate + Output: count(*) + -> Hash Semi Join + Hash Cond: ((a.unique1 = b.unique1) AND (a.two = (row_number() OVER (?)))) + -> Gather + Output: a.unique1, a.two + Workers Planned: 4 + -> Parallel Seq Scan on public.tenk1 a + Output: a.unique1, a.two + -> Hash + Output: b.unique1, (row_number() OVER (?)) + -> WindowAgg + Output: b.unique1, row_number() OVER (?) + -> Gather + Output: b.unique1 + Workers Planned: 4 + -> Parallel Index Only Scan using tenk1_unique1 on public.tenk1 b + Output: b.unique1 +(18 rows) + -- to increase the parallel query test coverage SAVEPOINT settings; SET LOCAL force_parallel_mode = 1; diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql index 7771e055ab9..3d1dffe61d2 100644 --- a/src/test/regress/sql/select_parallel.sql +++ b/src/test/regress/sql/select_parallel.sql @@ -362,6 +362,12 @@ select count(*) from tenk1; reset force_parallel_mode; reset role; +-- Window function calculation can't be pushed to workers. +explain (costs off, verbose) + select count(*) from tenk1 a where (unique1, two) in + (select unique1, row_number() over() from tenk1 b); + + -- to increase the parallel query test coverage SAVEPOINT settings; SET LOCAL force_parallel_mode = 1; |