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Re: Wrong plan sequential scan instead of an index one

From: Michael Fuhr <mike(at)fuhr(dot)org>
To: Gaetano Mendola <mendola(at)bigfoot(dot)com>
Cc: "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>, Claus Guttesen <kometen(at)gmail(dot)com>
Subject: Re: Wrong plan sequential scan instead of an index one
Date: 2007-03-30 10:55:34
Message-ID: 20070330105534.GA1737@winnie.fuhr.org (view raw or flat)
Thread:
Lists: pgsql-performance
On Fri, Mar 30, 2007 at 04:46:11AM -0600, Michael Fuhr wrote:
> Have you tried increasing the statistics target on l_pvcp.value?
> I ran your queries against canned data in 8.2.3 and better statistics
> resulted in more accurate row count estimates for this and other
> parts of the plan.  I don't recall if estimates for non-leading-character
> matches in earlier versions can benefit from better statistics.

This might work only in 8.2.  I see the following in the Release Notes:

* Improve the optimizer's selectivity estimates for LIKE, ILIKE,
  and regular expression operations (Tom)

-- 
Michael Fuhr

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