diff options
Diffstat (limited to 'src/backend/optimizer/path/joinrels.c')
| -rw-r--r-- | src/backend/optimizer/path/joinrels.c | 40 |
1 files changed, 29 insertions, 11 deletions
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c index e781ad5c1a8..ddecff55336 100644 --- a/src/backend/optimizer/path/joinrels.c +++ b/src/backend/optimizer/path/joinrels.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.105 2010/02/26 02:00:45 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.106 2010/09/14 23:15:29 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -29,7 +29,8 @@ static bool has_join_restriction(PlannerInfo *root, RelOptInfo *rel); static bool has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel); static bool is_dummy_rel(RelOptInfo *rel); static void mark_dummy_rel(RelOptInfo *rel); -static bool restriction_is_constant_false(List *restrictlist); +static bool restriction_is_constant_false(List *restrictlist, + bool only_pushed_down); /* @@ -603,7 +604,10 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) * * Also, a provably constant-false join restriction typically means that * we can skip evaluating one or both sides of the join. We do this by - * marking the appropriate rel as dummy. + * marking the appropriate rel as dummy. For outer joins, a constant-false + * restriction that is pushed down still means the whole join is dummy, + * while a non-pushed-down one means that no inner rows will join so we + * can treat the inner rel as dummy. * * We need only consider the jointypes that appear in join_info_list, plus * JOIN_INNER. @@ -612,7 +616,7 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) { case JOIN_INNER: if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || - restriction_is_constant_false(restrictlist)) + restriction_is_constant_false(restrictlist, false)) { mark_dummy_rel(joinrel); break; @@ -625,12 +629,13 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) restrictlist); break; case JOIN_LEFT: - if (is_dummy_rel(rel1)) + if (is_dummy_rel(rel1) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; } - if (restriction_is_constant_false(restrictlist) && + if (restriction_is_constant_false(restrictlist, false) && bms_is_subset(rel2->relids, sjinfo->syn_righthand)) mark_dummy_rel(rel2); add_paths_to_joinrel(root, joinrel, rel1, rel2, @@ -641,7 +646,8 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) restrictlist); break; case JOIN_FULL: - if (is_dummy_rel(rel1) && is_dummy_rel(rel2)) + if ((is_dummy_rel(rel1) && is_dummy_rel(rel2)) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; @@ -665,7 +671,7 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) bms_is_subset(sjinfo->min_righthand, rel2->relids)) { if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || - restriction_is_constant_false(restrictlist)) + restriction_is_constant_false(restrictlist, false)) { mark_dummy_rel(joinrel); break; @@ -687,6 +693,12 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) create_unique_path(root, rel2, rel2->cheapest_total_path, sjinfo) != NULL) { + if (is_dummy_rel(rel1) || is_dummy_rel(rel2) || + restriction_is_constant_false(restrictlist, false)) + { + mark_dummy_rel(joinrel); + break; + } add_paths_to_joinrel(root, joinrel, rel1, rel2, JOIN_UNIQUE_INNER, sjinfo, restrictlist); @@ -696,12 +708,13 @@ make_join_rel(PlannerInfo *root, RelOptInfo *rel1, RelOptInfo *rel2) } break; case JOIN_ANTI: - if (is_dummy_rel(rel1)) + if (is_dummy_rel(rel1) || + restriction_is_constant_false(restrictlist, true)) { mark_dummy_rel(joinrel); break; } - if (restriction_is_constant_false(restrictlist) && + if (restriction_is_constant_false(restrictlist, false) && bms_is_subset(rel2->relids, sjinfo->syn_righthand)) mark_dummy_rel(rel2); add_paths_to_joinrel(root, joinrel, rel1, rel2, @@ -947,9 +960,11 @@ mark_dummy_rel(RelOptInfo *rel) * join situations this will leave us computing cartesian products only to * decide there's no match for an outer row, which is pretty stupid. So, * we need to detect the case. + * + * If only_pushed_down is TRUE, then consider only pushed-down quals. */ static bool -restriction_is_constant_false(List *restrictlist) +restriction_is_constant_false(List *restrictlist, bool only_pushed_down) { ListCell *lc; @@ -964,6 +979,9 @@ restriction_is_constant_false(List *restrictlist) RestrictInfo *rinfo = (RestrictInfo *) lfirst(lc); Assert(IsA(rinfo, RestrictInfo)); + if (only_pushed_down && !rinfo->is_pushed_down) + continue; + if (rinfo->clause && IsA(rinfo->clause, Const)) { Const *con = (Const *) rinfo->clause; |