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| author | Robert Haas <rhaas@postgresql.org> | 2016-06-09 12:40:23 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2016-06-09 12:43:36 -0400 |
| commit | b12fd41c695b43c76b0a9a4d19ba43b05536440c (patch) | |
| tree | 966a7ca8b9c268b70f38257a56aeccaa25fd82b2 /src/backend/optimizer/util/relnode.c | |
| parent | e7bcd983f56136a9580076b60d5c19eb2fd83301 (diff) | |
| download | postgresql-b12fd41c695b43c76b0a9a4d19ba43b05536440c.tar.gz postgresql-b12fd41c695b43c76b0a9a4d19ba43b05536440c.zip | |
Don't generate parallel paths for rels with parallel-restricted outputs.
Such paths are unsafe. To make it cheaper to detect when this case
applies, track whether a relation's default PathTarget contains any
non-Vars. In most cases, the answer will be no, which enables us to
determine cheaply that the target list for a proposed path is
parallel-safe. However, subquery pull-up can create cases that
require us to inspect the target list more carefully.
Amit Kapila, reviewed by me.
Diffstat (limited to 'src/backend/optimizer/util/relnode.c')
| -rw-r--r-- | src/backend/optimizer/util/relnode.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/src/backend/optimizer/util/relnode.c b/src/backend/optimizer/util/relnode.c index e2ebf479296..2def06dd922 100644 --- a/src/backend/optimizer/util/relnode.c +++ b/src/backend/optimizer/util/relnode.c @@ -109,6 +109,7 @@ build_simple_rel(PlannerInfo *root, int relid, RelOptKind reloptkind) rel->consider_parallel = false; /* might get changed later */ rel->rel_parallel_workers = -1; /* set up in GetRelationInfo */ rel->reltarget = create_empty_pathtarget(); + rel->reltarget_has_non_vars = false; rel->pathlist = NIL; rel->ppilist = NIL; rel->partial_pathlist = NIL; @@ -396,6 +397,7 @@ build_join_rel(PlannerInfo *root, joinrel->consider_param_startup = false; joinrel->consider_parallel = false; joinrel->reltarget = create_empty_pathtarget(); + joinrel->reltarget_has_non_vars = false; joinrel->pathlist = NIL; joinrel->ppilist = NIL; joinrel->partial_pathlist = NIL; @@ -506,8 +508,8 @@ build_join_rel(PlannerInfo *root, * Set the consider_parallel flag if this joinrel could potentially be * scanned within a parallel worker. If this flag is false for either * inner_rel or outer_rel, then it must be false for the joinrel also. - * Even if both are true, there might be parallel-restricted quals at our - * level. + * Even if both are true, there might be parallel-restricted expressions + * in the targetlist or quals. * * Note that if there are more than two rels in this relation, they could * be divided between inner_rel and outer_rel in any arbitrary way. We @@ -517,7 +519,9 @@ build_join_rel(PlannerInfo *root, * here. */ if (inner_rel->consider_parallel && outer_rel->consider_parallel && - !has_parallel_hazard((Node *) restrictlist, false)) + !has_parallel_hazard((Node *) restrictlist, false) && + !(joinrel->reltarget_has_non_vars && + has_parallel_hazard((Node *) joinrel->reltarget->exprs, false))) joinrel->consider_parallel = true; /* |