diff options
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 33 |
1 files changed, 18 insertions, 15 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index bdc146a028e..bf8a28d1254 100644 --- a/src/backend/optimizer/plan/planner.c +++ b/src/backend/optimizer/plan/planner.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.162 2003/11/29 19:51:50 pgsql Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.163 2003/12/28 21:57:36 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -377,23 +377,13 @@ preprocess_expression(Query *parse, Node *expr, int kind) expr = flatten_join_alias_vars(parse, expr); /* - * Simplify constant expressions. - * - * Note that at this point quals have not yet been converted to - * implicit-AND form, so we can apply eval_const_expressions directly. - */ - expr = eval_const_expressions(expr); - - /* - * If it's a qual or havingQual, canonicalize it, and convert it to - * implicit-AND format. - * - * XXX Is there any value in re-applying eval_const_expressions after - * canonicalize_qual? + * If it's a qual or havingQual, canonicalize it. It seems most useful + * to do this before applying eval_const_expressions, since the latter + * can optimize flattened AND/ORs better than unflattened ones. */ if (kind == EXPRKIND_QUAL) { - expr = (Node *) canonicalize_qual((Expr *) expr, true); + expr = (Node *) canonicalize_qual((Expr *) expr); #ifdef OPTIMIZER_DEBUG printf("After canonicalize_qual()\n"); @@ -401,6 +391,19 @@ preprocess_expression(Query *parse, Node *expr, int kind) #endif } + /* + * Simplify constant expressions. + */ + expr = eval_const_expressions(expr); + + /* + * If it's a qual or havingQual, convert it to implicit-AND format. + * (We don't want to do this before eval_const_expressions, since the + * latter would be unable to simplify a top-level AND correctly.) + */ + if (kind == EXPRKIND_QUAL) + expr = (Node *) make_ands_implicit((Expr *) expr); + /* Expand SubLinks to SubPlans */ if (parse->hasSubLinks) expr = SS_process_sublinks(expr, (kind == EXPRKIND_QUAL)); |