diff options
Diffstat (limited to 'src/backend/optimizer/util/plancat.c')
| -rw-r--r-- | src/backend/optimizer/util/plancat.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c index 0ea9fcf7c20..ad715bbcc52 100644 --- a/src/backend/optimizer/util/plancat.c +++ b/src/backend/optimizer/util/plancat.c @@ -1142,7 +1142,27 @@ relation_excluded_by_constraints(PlannerInfo *root, List *safe_constraints; ListCell *lc; - /* Skip the test if constraint exclusion is disabled for the rel */ + /* + * Regardless of the setting of constraint_exclusion, detect + * constant-FALSE-or-NULL restriction clauses. Because const-folding will + * reduce "anything AND FALSE" to just "FALSE", any such case should + * result in exactly one baserestrictinfo entry. This doesn't fire very + * often, but it seems cheap enough to be worth doing anyway. (Without + * this, we'd miss some optimizations that 9.5 and earlier found via much + * more roundabout methods.) + */ + if (list_length(rel->baserestrictinfo) == 1) + { + RestrictInfo *rinfo = (RestrictInfo *) linitial(rel->baserestrictinfo); + Expr *clause = rinfo->clause; + + if (clause && IsA(clause, Const) && + (((Const *) clause)->constisnull || + !DatumGetBool(((Const *) clause)->constvalue))) + return true; + } + + /* Skip further tests if constraint exclusion is disabled for the rel */ if (constraint_exclusion == CONSTRAINT_EXCLUSION_OFF || (constraint_exclusion == CONSTRAINT_EXCLUSION_PARTITION && !(rel->reloptkind == RELOPT_OTHER_MEMBER_REL || |