From: Jim C. Nasby <jnasby@pervasive.com>
To: Sriram Dandapani <sdandapani@counterpane.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: multi column query
Date: Wed, 12 Apr 2006 19:43:41 -0500
Message-ID: <20060413004340.GQ49405@pervasive.com> (raw)
In-Reply-To: <6992E470F12A444BB787B5C937B9D4DF03EF488C@ca-mail1.cis.local>
References: <6992E470F12A444BB787B5C937B9D4DF03EF488C@ca-mail1.cis.local>
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
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To: pgsql-performance@postgresql.org
Cc: jnasby@pervasive.com, sdandapani@counterpane.com
Subject: Re: multi column query
In-Reply-To: <20060413004340.GQ49405@pervasive.com>
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