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help / color / mirror / Atom feedFrom: Joshua D. Drake <[email protected]>
To: George Pavlov <[email protected]>
Cc: Tom Lane <[email protected]>
Cc: [email protected]
Subject: Re: index vs. seq scan choice?
Date: Thu, 07 Jun 2007 15:59:06 -0700
Message-ID: <[email protected]> (raw)
In-Reply-To: <8C5B026B51B6854CBE88121DBF097A86DEA6D3@ehost010-33.exch010.intermedia.net>
References: <8C5B026B51B6854CBE88121DBF097A86C3A30D@ehost010-33.exch010.intermedia.net>
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George Pavlov wrote:
>> From: Tom Lane
>> "George Pavlov" <[email protected]> writes:
>>>> From: Joshua D. Drake [mailto:[email protected]]
>>>> 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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