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Re: Force another plan.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Fredrik Olsson <fredrik(dot)olsson(at)treyst(dot)se>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Force another plan.
Date: 2006-02-19 17:31:17
Message-ID: 11673.1140370277@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Fredrik Olsson <fredrik(dot)olsson(at)treyst(dot)se> writes:
>         ->  Seq Scan on t_entities  (cost=0.00..1.49 rows=7 width=4)
> (actual time=404.539..409.302 rows=2 loops=1)
>               Filter: ((haveaccess(createdby, responsible, "class",
> false) OR CASE WHEN (partof = 'contacts'::name) THEN
> ischildof(ancestorof(me()), "ID") ELSE false END) AND (subplan))
>               SubPlan
>                 ->  Function Scan on alleventoccurances
> (cost=0.00..12.50 rows=1000 width=8) (actual time=27.871..27.871 rows=0
> loops=14)

This seems to be your problem right here: evaluating that subplan for
each row of t_entities is pretty expensive, and yet the planner's
estimating a total cost of only 1.49 to run the scan.  What PG version
is this?  AFAICT we've accounted for subplan costs in scan quals for
a long time, certainly since 7.4.  Can you put together a self-contained
test case for this?

			regards, tom lane

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