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Re: Slow set-returning functions

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Merlin Moncure" <mmoncure(at)gmail(dot)com>
Cc: "Heikki Linnakangas" <heikki(at)enterprisedb(dot)com>, "Dean Rasheed" <dean_rasheed(at)hotmail(dot)com>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Slow set-returning functions
Date: 2008-01-20 18:30:35
Message-ID: 10405.1200853835@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
"Merlin Moncure" <mmoncure(at)gmail(dot)com> writes:
> prepared statements have the same problem.  IIRC the planner assumes
> 10%, which will often drop to a seqscan or a bitmap index scan.  Some
> years back I argued (unsuccessfully) to have the planner guess 100
> rows or something like that.  Ideally, I think it would generate the
> plan from the value passed into the first invocation of the function.

I believe it's the case that that will happen now in the same contexts
where the planner uses the first value of any other parameter (ie,
unnamed statements in the extended-query protocol).

			regards, tom lane

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