diff options
Diffstat (limited to 'src/backend/optimizer/geqo/geqo_eval.c')
| -rw-r--r-- | src/backend/optimizer/geqo/geqo_eval.c | 30 |
1 files changed, 21 insertions, 9 deletions
diff --git a/src/backend/optimizer/geqo/geqo_eval.c b/src/backend/optimizer/geqo/geqo_eval.c index 3460eb5b8e3..5d31ac738e7 100644 --- a/src/backend/optimizer/geqo/geqo_eval.c +++ b/src/backend/optimizer/geqo/geqo_eval.c @@ -6,7 +6,7 @@ * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * - * $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_eval.c,v 1.74 2005/06/05 22:32:55 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/geqo/geqo_eval.c,v 1.75 2005/06/08 23:02:04 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -47,7 +47,8 @@ geqo_eval(Gene *tour, int num_gene, GeqoEvalData *evaldata) MemoryContext oldcxt; RelOptInfo *joinrel; Cost fitness; - List *savelist; + int savelength; + struct HTAB *savehash; /* * Because gimme_tree considers both left- and right-sided trees, @@ -83,13 +84,19 @@ geqo_eval(Gene *tour, int num_gene, GeqoEvalData *evaldata) * gimme_tree will add entries to root->join_rel_list, which may or may * not already contain some entries. The newly added entries will be * recycled by the MemoryContextDelete below, so we must ensure that - * the list is restored to its former state before exiting. With the - * new List implementation, the easiest way is to make a duplicate list - * that gimme_tree can modify. + * the list is restored to its former state before exiting. We can + * do this by truncating the list to its original length. NOTE this + * assumes that any added entries are appended at the end! + * + * We also must take care not to mess up the outer join_rel_hash, + * if there is one. We can do this by just temporarily setting the + * link to NULL. (If we are dealing with enough join rels, which we + * very likely are, a new hash table will get built and used locally.) */ - savelist = evaldata->root->join_rel_list; + savelength = list_length(evaldata->root->join_rel_list); + savehash = evaldata->root->join_rel_hash; - evaldata->root->join_rel_list = list_copy(savelist); + evaldata->root->join_rel_hash = NULL; /* construct the best path for the given combination of relations */ joinrel = gimme_tree(tour, num_gene, evaldata); @@ -105,8 +112,13 @@ geqo_eval(Gene *tour, int num_gene, GeqoEvalData *evaldata) else fitness = DBL_MAX; - /* restore join_rel_list */ - evaldata->root->join_rel_list = savelist; + /* + * Restore join_rel_list to its former state, and put back original + * hashtable if any. + */ + evaldata->root->join_rel_list = list_truncate(evaldata->root->join_rel_list, + savelength); + evaldata->root->join_rel_hash = savehash; /* release all the memory acquired within gimme_tree */ MemoryContextSwitchTo(oldcxt); |