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Re: getting an index to work with partial indices ...

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: "Marc G(dot) Fournier" <scrappy(at)postgresql(dot)org>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: getting an index to work with partial indices ...
Date: 2005-08-29 20:19:05
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
"Marc G. Fournier" <scrappy(at)postgresql(dot)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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