Skip site navigation (1) Skip section navigation (2)

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: 12790.1125346745@sss.pgh.pa.us (view raw or flat)
Thread:
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

In response to

pgsql-performance by date

Next:From: Michael FuhrDate: 2005-08-29 20:28:56
Subject: Re: Weird performance drop after VACUUM
Previous:From: Thomas F. O'ConnellDate: 2005-08-29 20:15:21
Subject: Re: Need indexes on empty tables for good performance ?

Privacy Policy | About PostgreSQL
Copyright © 1996-2014 The PostgreSQL Global Development Group