diff options
Diffstat (limited to 'src/backend/optimizer/plan/planmain.c')
| -rw-r--r-- | src/backend/optimizer/plan/planmain.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c index 6b6bc15bda7..abb468aa8d1 100644 --- a/src/backend/optimizer/plan/planmain.c +++ b/src/backend/optimizer/plan/planmain.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.57 2000/07/27 04:51:04 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/planmain.c,v 1.58 2000/08/13 02:50:07 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -78,7 +78,8 @@ query_planner(Query *root, List *qual, double tuple_fraction) { - List *constant_qual = NIL; + List *noncachable_qual; + List *constant_qual; List *var_only_tlist; Plan *subplan; @@ -106,9 +107,14 @@ query_planner(Query *root, * have been optimized away by eval_const_expressions(). What we're * mostly interested in here is quals that depend only on outer-level * vars, although if the qual reduces to "WHERE FALSE" this path will - * also be taken. + * also be taken. We also need a special case for quals that contain + * noncachable functions but no vars, such as "WHERE random() < 0.5". + * These cannot be treated as normal restriction or join quals, but + * they're not constants either. Instead, attach them to the qpqual + * of the top-level plan, so that they get evaluated once per potential + * output tuple. */ - qual = pull_constant_clauses(qual, &constant_qual); + qual = pull_constant_clauses(qual, &noncachable_qual, &constant_qual); /* * Create a target list that consists solely of (resdom var) target @@ -129,6 +135,12 @@ query_planner(Query *root, subplan = subplanner(root, var_only_tlist, qual, tuple_fraction); /* + * Handle the noncachable quals. + */ + if (noncachable_qual) + subplan->qual = nconc(subplan->qual, noncachable_qual); + + /* * Build a result node to control the plan if we have constant quals. */ if (constant_qual) @@ -163,7 +175,7 @@ query_planner(Query *root, * for processing a single level of attributes. * * flat_tlist is the flattened target list - * qual is the qualification to be satisfied + * qual is the qualification to be satisfied (restrict and join quals only) * tuple_fraction is the fraction of tuples we expect will be retrieved * * See query_planner() comments about the interpretation of tuple_fraction. |