diff options
Diffstat (limited to 'src/backend/optimizer/plan/planmain.c')
| -rw-r--r-- | src/backend/optimizer/plan/planmain.c | 39 |
1 files changed, 37 insertions, 2 deletions
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c index c8d43a54657..ae44e2bc35c 100644 --- a/src/backend/optimizer/plan/planmain.c +++ b/src/backend/optimizer/plan/planmain.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.95 2006/07/14 14:52:20 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.96 2006/09/19 22:49:52 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -85,6 +85,8 @@ query_planner(PlannerInfo *root, List *tlist, double tuple_fraction, RelOptInfo *final_rel; Path *cheapestpath; Path *sortedpath; + Index rti; + double total_pages; /* Make tuple_fraction accessible to lower-level routines */ root->tuple_fraction = tuple_fraction; @@ -122,11 +124,44 @@ query_planner(PlannerInfo *root, List *tlist, double tuple_fraction, root->oj_info_list = NIL; /* - * Construct RelOptInfo nodes for all base relations in query. + * Construct RelOptInfo nodes for all base relations in query, and + * indirectly for all appendrel member relations ("other rels"). This + * will give us a RelOptInfo for every "simple" (non-join) rel involved + * in the query. + * + * Note: the reason we find the rels by searching the jointree and + * appendrel list, rather than just scanning the rangetable, is that the + * rangetable may contain RTEs for rels not actively part of the query, + * for example views. We don't want to make RelOptInfos for them. */ add_base_rels_to_query(root, (Node *) parse->jointree); /* + * We should now have size estimates for every actual table involved + * in the query, so we can compute total_table_pages. Note that + * appendrels are not double-counted here, even though we don't bother + * to distinguish RelOptInfos for appendrel parents, because the parents + * will still have size zero. + * + * XXX if a table is self-joined, we will count it once per appearance, + * which perhaps is the wrong thing ... but that's not completely clear, + * and detecting self-joins here is difficult, so ignore it for now. + */ + total_pages = 0; + for (rti = 1; rti < root->simple_rel_array_size; rti++) + { + RelOptInfo *brel = root->simple_rel_array[rti]; + + if (brel == NULL) + continue; + + Assert(brel->relid == rti); /* sanity check on array */ + + total_pages += (double) brel->pages; + } + root->total_table_pages = total_pages; + + /* * Examine the targetlist and qualifications, adding entries to baserel * targetlists for all referenced Vars. Restrict and join clauses are * added to appropriate lists belonging to the mentioned relations. We |