diff options
Diffstat (limited to 'src/backend/optimizer/util/restrictinfo.c')
| -rw-r--r-- | src/backend/optimizer/util/restrictinfo.c | 32 |
1 files changed, 29 insertions, 3 deletions
diff --git a/src/backend/optimizer/util/restrictinfo.c b/src/backend/optimizer/util/restrictinfo.c index 20590a98e0e..4349143e946 100644 --- a/src/backend/optimizer/util/restrictinfo.c +++ b/src/backend/optimizer/util/restrictinfo.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.31 2004/12/31 22:00:23 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.31.4.1 2007/07/31 19:54:10 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -31,6 +31,8 @@ static Expr *make_sub_restrictinfos(Expr *clause, static RestrictInfo *join_clause_is_redundant(Query *root, RestrictInfo *rinfo, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype); @@ -314,6 +316,8 @@ get_actual_join_clauses(List *restrictinfo_list, */ List * remove_redundant_join_clauses(Query *root, List *restrictinfo_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { List *result = NIL; @@ -341,7 +345,9 @@ remove_redundant_join_clauses(Query *root, List *restrictinfo_list, RestrictInfo *prevrinfo; /* is it redundant with any prior clause? */ - prevrinfo = join_clause_is_redundant(root, rinfo, result, jointype); + prevrinfo = join_clause_is_redundant(root, rinfo, result, + outer_relids, inner_relids, + jointype); if (prevrinfo == NULL) { /* no, so add it to result list */ @@ -377,6 +383,8 @@ List * select_nonredundant_join_clauses(Query *root, List *restrictinfo_list, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { List *result = NIL; @@ -387,7 +395,9 @@ select_nonredundant_join_clauses(Query *root, RestrictInfo *rinfo = (RestrictInfo *) lfirst(item); /* drop it if redundant with any reference clause */ - if (join_clause_is_redundant(root, rinfo, reference_list, jointype) != NULL) + if (join_clause_is_redundant(root, rinfo, reference_list, + outer_relids, inner_relids, + jointype) != NULL) continue; /* otherwise, add it to result list */ @@ -420,6 +430,12 @@ select_nonredundant_join_clauses(Query *root, * of the latter, even though they might seem redundant by the pathkey * membership test. * + * Also, we cannot eliminate clauses wherein one side mentions vars from + * both relations, as in "WHERE t1.f1 = t2.f1 AND t1.f1 = t1.f2 - t2.f2". + * In this example, "t1.f2 - t2.f2" could not have been computed at all + * before forming the join of t1 and t2, so it certainly wasn't constrained + * earlier. + * * Weird special case: if we have two clauses that seem redundant * except one is pushed down into an outer join and the other isn't, * then they're not really redundant, because one constrains the @@ -429,6 +445,8 @@ static RestrictInfo * join_clause_is_redundant(Query *root, RestrictInfo *rinfo, List *reference_list, + Relids outer_relids, + Relids inner_relids, JoinType jointype) { ListCell *refitem; @@ -450,6 +468,14 @@ join_clause_is_redundant(Query *root, bms_is_empty(rinfo->right_relids)) return NULL; /* var = const, so not redundant */ + /* check for either side mentioning both rels */ + if (bms_overlap(rinfo->left_relids, outer_relids) && + bms_overlap(rinfo->left_relids, inner_relids)) + return NULL; /* clause LHS uses both, so not redundant */ + if (bms_overlap(rinfo->right_relids, outer_relids) && + bms_overlap(rinfo->right_relids, inner_relids)) + return NULL; /* clause RHS uses both, so not redundant */ + cache_mergeclause_pathkeys(root, rinfo); foreach(refitem, reference_list) |