diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index 00493d82e77..f84dcdfd1be 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -768,7 +768,12 @@ generate_base_implied_equalities_const(PlannerInfo *root, } } - /* Find the constant member to use */ + /* + * Find the constant member to use. We prefer an actual constant to + * pseudo-constants (such as Params), because the constraint exclusion + * machinery might be able to exclude relations on the basis of generated + * "var = const" equalities, but "var = param" won't work for that. + */ foreach(lc, ec->ec_members) { EquivalenceMember *cur_em = (EquivalenceMember *) lfirst(lc); @@ -776,7 +781,8 @@ generate_base_implied_equalities_const(PlannerInfo *root, if (cur_em->em_is_const) { const_em = cur_em; - break; + if (IsA(cur_em->em_expr, Const)) + break; } } Assert(const_em != NULL); |