Message-ID: <46688DBA.7000800@commandprompt.com>
Date: Thu, 07 Jun 2007 15:59:06 -0700
From: "Joshua D. Drake" <jd@commandprompt.com>
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To: George Pavlov <gpavlov@mynewplace.com>
CC: Tom Lane <tgl@sss.pgh.pa.us>, pgsql-general@postgresql.org
Subject: Re: index vs. seq scan choice?
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	<27828.1180055291@sss.pgh.pa.us>
	<8C5B026B51B6854CBE88121DBF097A86DEA6B4@ehost010-33.exch010.intermedia.net>
	<4668804F.6090201@commandprompt.com>
	<8C5B026B51B6854CBE88121DBF097A86DEA6C5@ehost010-33.exch010.intermedia.net>
	<415.1181255628@sss.pgh.pa.us>
	<8C5B026B51B6854CBE88121DBF097A86DEA6D3@ehost010-33.exch010.intermedia.net>
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George Pavlov wrote:
>> From: Tom Lane
>> "George Pavlov" <gpavlov@mynewplace.com> writes:
>>>> From: Joshua D. Drake [mailto:jd@commandprompt.com]
>>>> In those rare cases wouldn't it make more sense to just set
>>>> enable_seqscan to off; run query; set enable_seqscan to on;
>>> 1. these cases are not that rare (to me);
>> It strikes me that you probably need to adjust the planner cost
>> parameters to reflect reality on your system.  Usually dropping
>> random_page_cost is the way to bias the thing more in favor of
>> index scans.
> 
> Thanks, Tom, I will try that. Seems better than fiddling with
> enable_seqscan around every query/transaction.
> 
> Joshua, I fail to understand why setting and unsetting enable_seqscan on
> a per query/transaction basis is in any way preferable to query hints?
> Don't get me wrong, I don't like the idea of hints, and I have read the
> archives on the subject and I agree with the philosophy, but if the
> optimization toolkit for routine application queries is going to include
> setting config parameters that just smacks of hints by another name...

I actually have zero opinion on hints, my comment was more about opening 
the wasps nest of the hints discussion more than anything :)

Joshua D. Drake


> 
> George
> 


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