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 fa53b7a8c50..82b56902a6c 100644 --- a/src/backend/optimizer/util/clauses.c +++ b/src/backend/optimizer/util/clauses.c @@ -1168,13 +1168,27 @@ 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 562eb2c5380..9fd86256d2f 100644 --- a/src/test/regress/expected/select_parallel.out +++ b/src/test/regress/expected/select_parallel.out @@ -573,6 +573,32 @@ explain (costs off) Index Cond: (unique1 = 1) (5 rows) +-- 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 EXPLAIN (analyze, timing off, summary off, costs off) SELECT * FROM tenk1; QUERY PLAN diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql index 1d29e966076..dd9365d7c6e 100644 --- a/src/test/regress/sql/select_parallel.sql +++ b/src/test/regress/sql/select_parallel.sql @@ -204,6 +204,12 @@ set force_parallel_mode=1; explain (costs off) select stringu1::int2 from tenk1 where unique1 = 1; +-- 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 EXPLAIN (analyze, timing off, summary off, costs off) SELECT * FROM tenk1; |