diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/optimizer/plan/createplan.c | 45 |
1 files changed, 44 insertions, 1 deletions
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index bfb97bc1eb5..f872ca3fdda 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -10,7 +10,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.101 2000/11/16 22:30:24 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/plan/createplan.c,v 1.102 2000/12/23 18:49:41 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -1733,6 +1733,49 @@ make_limit(List *tlist, Plan *lefttree, copy_plan_costsize(plan, lefttree); + /* + * If offset/count are constants, adjust the output rows count and costs + * accordingly. This is only a cosmetic issue if we are at top level, + * but if we are building a subquery then it's important to report + * correct info to the outer planner. + */ + if (limitOffset && IsA(limitOffset, Const)) + { + Const *limito = (Const *) limitOffset; + int32 offset = DatumGetInt32(limito->constvalue); + + if (!limito->constisnull && offset > 0) + { + if (offset > plan->plan_rows) + offset = (int32) plan->plan_rows; + if (plan->plan_rows > 0) + plan->startup_cost += + (plan->total_cost - plan->startup_cost) + * ((double) offset) / plan->plan_rows; + plan->plan_rows -= offset; + if (plan->plan_rows < 1) + plan->plan_rows = 1; + } + } + if (limitCount && IsA(limitCount, Const)) + { + Const *limitc = (Const *) limitCount; + int32 count = DatumGetInt32(limitc->constvalue); + + if (!limitc->constisnull && count >= 0) + { + if (count > plan->plan_rows) + count = (int32) plan->plan_rows; + if (plan->plan_rows > 0) + plan->total_cost = plan->startup_cost + + (plan->total_cost - plan->startup_cost) + * ((double) count) / plan->plan_rows; + plan->plan_rows = count; + if (plan->plan_rows < 1) + plan->plan_rows = 1; + } + } + plan->state = (EState *) NULL; plan->targetlist = tlist; plan->qual = NIL; |