diff options
Diffstat (limited to 'src/backend/optimizer/plan/planner.c')
| -rw-r--r-- | src/backend/optimizer/plan/planner.c | 23 |
1 files changed, 14 insertions, 9 deletions
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c index bf8a28d125..7af46244bb 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 1.163 2003/12/28 21:57:36 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/optimizer/plan/planner.c,v 1.164 2004/01/12 22:20:28 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -380,6 +380,10 @@ preprocess_expression(Query *parse, Node *expr, int kind) * 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. + * + * Note: all processing of a qual expression after this point must be + * careful to maintain AND/OR flatness --- that is, do not generate a + * tree with AND directly under AND, nor OR directly under OR. */ if (kind == EXPRKIND_QUAL) { @@ -396,14 +400,6 @@ preprocess_expression(Query *parse, Node *expr, int kind) */ 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)); @@ -417,6 +413,15 @@ preprocess_expression(Query *parse, Node *expr, int kind) if (PlannerQueryLevel > 1) expr = SS_replace_correlation_vars(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. Also, + * SS_process_sublinks expects explicit-AND format.) + */ + if (kind == EXPRKIND_QUAL) + expr = (Node *) make_ands_implicit((Expr *) expr); + return expr; } |