diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/path/equivclass.c | 49 |
1 files changed, 36 insertions, 13 deletions
diff --git a/src/backend/optimizer/path/equivclass.c b/src/backend/optimizer/path/equivclass.c index e9bd5eaff5c..b50e9ccdf14 100644 --- a/src/backend/optimizer/path/equivclass.c +++ b/src/backend/optimizer/path/equivclass.c @@ -2135,11 +2135,10 @@ add_child_rel_equivalences(PlannerInfo *root, continue; /* - * No point in searching if parent rel not mentioned in eclass; but we - * can't tell that for sure if parent rel is itself a child. + * No point in searching if child's topmost parent rel is not + * mentioned in eclass. */ - if (parent_rel->reloptkind == RELOPT_BASEREL && - !bms_is_subset(parent_rel->relids, cur_ec->ec_relids)) + if (!bms_is_subset(child_rel->top_parent_relids, cur_ec->ec_relids)) continue; foreach(lc2, cur_ec->ec_members) @@ -2149,18 +2148,41 @@ add_child_rel_equivalences(PlannerInfo *root, if (cur_em->em_is_const) continue; /* ignore consts here */ - /* Does it reference parent_rel? */ - if (bms_overlap(cur_em->em_relids, parent_rel->relids)) + /* + * We consider only original EC members here, not + * already-transformed child members. Otherwise, if some original + * member expression references more than one appendrel, we'd get + * an O(N^2) explosion of useless derived expressions for + * combinations of children. + */ + if (cur_em->em_is_child) + continue; /* ignore children here */ + + /* Does this member reference child's topmost parent rel? */ + if (bms_overlap(cur_em->em_relids, child_rel->top_parent_relids)) { /* Yes, generate transformed child version */ Expr *child_expr; Relids new_relids; Relids new_nullable_relids; - child_expr = (Expr *) - adjust_appendrel_attrs(root, - (Node *) cur_em->em_expr, - 1, &appinfo); + if (parent_rel->reloptkind == RELOPT_BASEREL) + { + /* Simple single-level transformation */ + child_expr = (Expr *) + adjust_appendrel_attrs(root, + (Node *) cur_em->em_expr, + 1, &appinfo); + } + else + { + /* Must do multi-level transformation */ + child_expr = (Expr *) + adjust_appendrel_attrs_multilevel(root, + (Node *) cur_em->em_expr, + child_rel->relids, + child_rel->top_parent_relids); + } /* * Transform em_relids to match. Note we do *not* do @@ -2169,7 +2191,7 @@ add_child_rel_equivalences(PlannerInfo *root, * don't want the child member to be marked as constant. */ new_relids = bms_difference(cur_em->em_relids, - parent_rel->relids); + child_rel->top_parent_relids); new_relids = bms_add_members(new_relids, child_rel->relids); /* @@ -2177,10 +2199,11 @@ add_child_rel_equivalences(PlannerInfo *root, * parent and child relids are singletons. */ new_nullable_relids = cur_em->em_nullable_relids; - if (bms_overlap(new_nullable_relids, parent_rel->relids)) + if (bms_overlap(new_nullable_relids, + child_rel->top_parent_relids)) { new_nullable_relids = bms_difference(new_nullable_relids, - parent_rel->relids); + child_rel->top_parent_relids); new_nullable_relids = bms_add_members(new_nullable_relids, child_rel->relids); } |