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Loosen the restriction outer path has Motion of parallel plan #134

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Merged
avamingli merged 1 commit into from
Aug 24, 2023
Merged

Loosen the restriction outer path has Motion of parallel plan #134

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7 changes: 5 additions & 2 deletions src/backend/optimizer/util/pathnode.c
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Expand Up @@ -4483,9 +4483,12 @@ create_hashjoin_path(PlannerInfo *root,
/*
* For parallel hash, it is motionHazard. If there are parallel hash join on outside child,
* not use parallel hash.
* CBDB_PARALLEL_FIXME: At least, should not have impact on non-parallel path generation.
* CBDB_PARALLEL_FIXME:
* At least, should not have impact on non-parallel path generation and when there are no
* parallel-aware paths.
*/
if (enable_parallel && outer_path->barrierHazard && !parallel_hash)
if (enable_parallel && enable_parallel_hash &&
outer_path->barrierHazard && !parallel_hash)
return NULL;

if (parallel_hash && outer_path->barrierHazard)
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33 changes: 33 additions & 0 deletions src/test/regress/expected/gp_parallel.out
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Expand Up @@ -1847,6 +1847,39 @@ abort;
--
-- End of Test locus after eliding mtion node.
--
--
-- Test outer path has Motion of parallel plan.
--
begin;
create table t1(a int, b int) with(parallel_workers=3);
create table t2(b int, a int) with(parallel_workers=2);
insert into t1 select i, i+1 from generate_series(1, 10) i;
insert into t2 select i, i+1 from generate_series(1, 5) i;
analyze t1;
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analyze t2;
set local optimizer=off;
set local enable_parallel=on;
set local enable_parallel_hash=off;
set local max_parallel_workers_per_gather= 4;
explain(costs off) select * from t1 right join t2 on t1.b = t2.a;
QUERY PLAN
------------------------------------------------------------------
Gather Motion 6:1 (slice1; segments: 6)
-> Hash Left Join
Hash Cond: (t2.a = t1.b)
-> Redistribute Motion 6:6 (slice2; segments: 6)
Hash Key: t2.a
Hash Module: 3
-> Parallel Seq Scan on t2
-> Hash
-> Redistribute Motion 3:6 (slice3; segments: 3)
Hash Key: t1.b
Hash Module: 3
-> Seq Scan on t1
Optimizer: Postgres query optimizer
(13 rows)

abort;
-- start_ignore
drop schema test_parallel cascade;
-- end_ignore
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17 changes: 17 additions & 0 deletions src/test/regress/sql/gp_parallel.sql
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Expand Up @@ -561,6 +561,23 @@ abort;
-- End of Test locus after eliding mtion node.
--

--
-- Test outer path has Motion of parallel plan.
--
begin;
create table t1(a int, b int) with(parallel_workers=3);
create table t2(b int, a int) with(parallel_workers=2);
insert into t1 select i, i+1 from generate_series(1, 10) i;
insert into t2 select i, i+1 from generate_series(1, 5) i;
analyze t1;
analyze t2;
set local optimizer=off;
set local enable_parallel=on;
set local enable_parallel_hash=off;
set local max_parallel_workers_per_gather= 4;
explain(costs off) select * from t1 right join t2 on t1.b = t2.a;
abort;

-- start_ignore
drop schema test_parallel cascade;
-- end_ignore
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