diff options
| -rw-r--r-- | src/backend/optimizer/path/pathkeys.c | 88 |
1 files changed, 61 insertions, 27 deletions
diff --git a/src/backend/optimizer/path/pathkeys.c b/src/backend/optimizer/path/pathkeys.c index 23bab208751..fb5d38255db 100644 --- a/src/backend/optimizer/path/pathkeys.c +++ b/src/backend/optimizer/path/pathkeys.c @@ -11,7 +11,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.77 2006/07/14 14:52:20 momjian Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.78 2006/08/17 17:02:49 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1059,39 +1059,73 @@ convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel, { PathKeyItem *sub_item = (PathKeyItem *) lfirst(j); Node *sub_key = sub_item->key; + Expr *rtarg; ListCell *k; + /* + * We handle two cases: the sub_pathkey key can be either an exact + * match for a targetlist entry, or a RelabelType of a targetlist + * entry. (The latter case is worth extra code because it arises + * frequently in connection with varchar fields.) + */ + if (IsA(sub_key, RelabelType)) + rtarg = ((RelabelType *) sub_key)->arg; + else + rtarg = NULL; + foreach(k, sub_tlist) { TargetEntry *tle = (TargetEntry *) lfirst(k); + Node *outer_expr; + PathKeyItem *outer_item; + int score; - if (!tle->resjunk && - equal(tle->expr, sub_key)) + /* resjunk items aren't visible to outer query */ + if (tle->resjunk) + continue; + + if (equal(tle->expr, sub_key)) { - /* Found a representation for this sub_key */ - Var *outer_var; - PathKeyItem *outer_item; - int score; - - outer_var = makeVar(rel->relid, - tle->resno, - exprType((Node *) tle->expr), - exprTypmod((Node *) tle->expr), - 0); - outer_item = makePathKeyItem((Node *) outer_var, - sub_item->sortop, - true); - /* score = # of mergejoin peers */ - score = count_canonical_peers(root, outer_item); - /* +1 if it matches the proper query_pathkeys item */ - if (retvallen < outer_query_keys && - list_member(list_nth(root->query_pathkeys, retvallen), outer_item)) - score++; - if (score > best_score) - { - best_item = outer_item; - best_score = score; - } + /* Exact match */ + outer_expr = (Node *) + makeVar(rel->relid, + tle->resno, + exprType((Node *) tle->expr), + exprTypmod((Node *) tle->expr), + 0); + } + else if (rtarg && equal(tle->expr, rtarg)) + { + /* Match after discarding RelabelType */ + outer_expr = (Node *) + makeVar(rel->relid, + tle->resno, + exprType((Node *) tle->expr), + exprTypmod((Node *) tle->expr), + 0); + outer_expr = (Node *) + makeRelabelType((Expr *) outer_expr, + ((RelabelType *) sub_key)->resulttype, + ((RelabelType *) sub_key)->resulttypmod, + ((RelabelType *) sub_key)->relabelformat); + } + else + continue; + + /* Found a representation for this sub_key */ + outer_item = makePathKeyItem(outer_expr, + sub_item->sortop, + true); + /* score = # of mergejoin peers */ + score = count_canonical_peers(root, outer_item); + /* +1 if it matches the proper query_pathkeys item */ + if (retvallen < outer_query_keys && + list_member(list_nth(root->query_pathkeys, retvallen), outer_item)) + score++; + if (score > best_score) + { + best_item = outer_item; + best_score = score; } } } |