diff options
Diffstat (limited to 'src/backend/optimizer/path/allpaths.c')
| -rw-r--r-- | src/backend/optimizer/path/allpaths.c | 47 |
1 files changed, 32 insertions, 15 deletions
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c index 07a99e9c6b7..0ad3dc5aae1 100644 --- a/src/backend/optimizer/path/allpaths.c +++ b/src/backend/optimizer/path/allpaths.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.163 2007/04/21 21:01:44 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.164 2007/05/26 18:23:01 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -45,6 +45,7 @@ static void set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte); static void set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte); +static void set_dummy_rel_pathlist(RelOptInfo *rel); static void set_subquery_pathlist(PlannerInfo *root, RelOptInfo *rel, Index rti, RangeTblEntry *rte); static void set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, @@ -198,23 +199,14 @@ set_plain_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte) { /* * If we can prove we don't need to scan the rel via constraint exclusion, - * set up a single dummy path for it. (Rather than inventing a special - * "dummy" path type, we represent this as an AppendPath with no members.) - * We only need to check for regular baserels; if it's an otherrel, CE - * was already checked in set_append_rel_pathlist(). + * set up a single dummy path for it. We only need to check for regular + * baserels; if it's an otherrel, CE was already checked in + * set_append_rel_pathlist(). */ if (rel->reloptkind == RELOPT_BASEREL && relation_excluded_by_constraints(rel, rte)) { - /* Set dummy size estimates --- we leave attr_widths[] as zeroes */ - rel->rows = 0; - rel->width = 0; - - add_path(rel, (Path *) create_append_path(rel, NIL)); - - /* Select cheapest path (pretty easy in this case...) */ - set_cheapest(rel); - + set_dummy_rel_pathlist(rel); return; } @@ -330,7 +322,12 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, if (relation_excluded_by_constraints(childrel, childRTE)) { - /* this child need not be scanned, so just disregard it */ + /* + * This child need not be scanned, so we can omit it from the + * appendrel. Mark it with a dummy cheapest-path though, in + * case best_appendrel_indexscan() looks at it later. + */ + set_dummy_rel_pathlist(childrel); continue; } @@ -425,6 +422,26 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel, set_cheapest(rel); } +/* + * set_dummy_rel_pathlist + * Build a dummy path for a relation that's been excluded by constraints + * + * Rather than inventing a special "dummy" path type, we represent this as an + * AppendPath with no members. + */ +static void +set_dummy_rel_pathlist(RelOptInfo *rel) +{ + /* Set dummy size estimates --- we leave attr_widths[] as zeroes */ + rel->rows = 0; + rel->width = 0; + + add_path(rel, (Path *) create_append_path(rel, NIL)); + + /* Select cheapest path (pretty easy in this case...) */ + set_cheapest(rel); +} + /* quick-and-dirty test to see if any joining is needed */ static bool has_multiple_baserels(PlannerInfo *root) |