From: Tom Lane <tgl@sss.pgh.pa.us>
To: Marc G. Fournier <scrappy@postgresql.org>
Cc: pgsql-performance@postgresql.org
Subject: Re: getting an index to work with partial indices ...
Date: Mon, 29 Aug 2005 16:19:05 -0400
Message-ID: <12790.1125346745@sss.pgh.pa.us> (raw)
In-Reply-To: <20050829165335.X1044@ganymede.hub.org>
References: <20050829165335.X1044@ganymede.hub.org>
"Marc G. Fournier" <scrappy@postgresql.org> writes:
> But, ti will if I try 'priority = -2' ... what is teh threshhold for using
> the index? obviously 10% of the records is too high ...
Depends on a lot of factors, but usually somewhere between 1% and 10%.
(The new bitmap index scan code in 8.1 should be workable for higher
percentages.) If this doesn't seem to square with reality for you,
you might try reducing random_page_cost.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, scrappy@postgresql.org
Subject: Re: getting an index to work with partial indices ...
In-Reply-To: <12790.1125346745@sss.pgh.pa.us>
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