Re: multi column query - Mailing list pgsql-performance

From Jim C. Nasby
Subject Re: multi column query
Date
Msg-id 20060413004340.GQ49405@pervasive.com
Whole thread Raw
In response to multi column query  ("Sriram Dandapani" <sdandapani@counterpane.com>)
List pgsql-performance
On Wed, Apr 12, 2006 at 05:32:32PM -0700, Sriram Dandapani wrote:
> Hi
>
> When I update a table that has 20 columns and the where clause includes
> 16 of the columns (this is a data warehousing type update on aggregate
> fields),
>
> The bitmap scan is not used by the optimizer. The table is indexed on 3
> of the 20 fields. The update takes really long to finish (on a 6 million
> row table)
>
> Do I need to do some "magic" with configuration to turn on bitmap scans.

No. What's explain analyze of the query show? What's it doing now?
Seqscan? You might try set enable_seqscan=off and see what that does.
--
Jim C. Nasby, Sr. Engineering Consultant      jnasby@pervasive.com
Pervasive Software      http://pervasive.com    work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf       cell: 512-569-9461

pgsql-performance by date:

Previous
From: Tom Lane
Date:
Subject: Re: pgmemcache
Next
From: Francisco Reyes
Date:
Subject: Inserts optimization?