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Re: Enabling and Disabling Sequencial Scan

From: "Nikolaus Dilger" <nikolaus(at)dilger(dot)cc>
To: yusuf0478(at)netscape(dot)net
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Enabling and Disabling Sequencial Scan
Date: 2003-05-31 15:07:15
Message-ID: 20030531080716.20944.h004.c001.wm@mail.dilger.cc.criticalpath.net (view raw or flat)
Thread:
Lists: pgsql-performance
David,

I say go ahead and use it since you get a significant
performance gain.  This is a special case where you
know more about your data than the planer does with
general system wide settings.  In Oracle you could use
"hints".  Since there are no hints in PostgreSQL
disabling and reenabling an option just before and
after a query has the same effect.

Regards,
Nikolaus

On Fri, 30 May 2003 16:33:07 -0400, Yusuf wrote:

> 
> In the application, that I'm working on, I have a
query
> that'll be a lot 
> 60% faster if I disable sequential scan forcing it to
> you my index.
> 
> Is it bad practice to disable sequential scan ( set 
> enable_seqscan=false), run my query then enable
> sequential scan, 
> whenever I'm running this query?  Why?
> 
> Thanks in advance
> 
> - David Wendy
> 
> 
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