diff options
Diffstat (limited to 'src/backend/optimizer/path/pathkeys.c')
| -rw-r--r-- | src/backend/optimizer/path/pathkeys.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index b578e33f5c8..d5fbf82eb50 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.19 2000/02/15 20:49:17 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/pathkeys.c,v 1.20 2000/02/18 23:47:19 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -778,6 +778,7 @@ make_pathkeys_for_mergeclauses(Query *root, Node *key; Oid sortop; PathKeyItem *item; + List *pathkey; Assert(restrictinfo->mergejoinoperator != InvalidOid); @@ -791,10 +792,21 @@ make_pathkeys_for_mergeclauses(Query *root, key = (Node *) get_leftop(restrictinfo->clause); sortop = restrictinfo->left_sortop; /* - * Add a pathkey sublist for this sort item + * Find pathkey sublist for this sort item. We expect to find + * the canonical set including the mergeclause's left and right + * sides; if we get back just the one item, something is rotten. */ item = makePathKeyItem(key, sortop); - pathkeys = lappend(pathkeys, make_canonical_pathkey(root, item)); + pathkey = make_canonical_pathkey(root, item); + Assert(length(pathkey) > 1); + /* + * Since the item we just made is not in the returned canonical set, + * we can free it --- this saves a useful amount of storage in a + * big join tree. + */ + pfree(item); + + pathkeys = lappend(pathkeys, pathkey); } return pathkeys; |