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From: Csaba Nagy <nagy@ecircle-ag.com>
To: Bill Moran <wmoran@collaborativefusion.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: TB-sized databases
Date: Wed, 28 Nov 2007 14:48:22 +0100
Message-ID: <1196257702.31315.6.camel@PCD12478> (raw)
In-Reply-To: <20071128082716.91bbad9c.wmoran@collaborativefusion.com>
References: <4544e0330711260904g45d893a8ub1731e245aa8fc84@mail.gmail.com>
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	<474B1B8C.1030505@gmail.com>
	<4544e0330711271218h56ce4cc3p280a9fefff24583d@mail.gmail.com>
	<1196197045.4246.1154.camel@ebony.site>
	<474CA2FA.2020201@laotraesquina.com.ar>
	<Pine.LNX.4.58.0711281248290.3731@aragorn.flymine.org>
	<20071128082716.91bbad9c.wmoran@collaborativefusion.com>

On Wed, 2007-11-28 at 08:27 -0500, Bill Moran wrote:
> Is there something wrong with:
> set enable_seqscan = off
> ?

Nothing wrong with enable_seqscan = off except it is all or nothing type
of thing... if you want the big table to never use seqscan, but a medium
table which is joined in should use it, then what you do ? And setting
enable_seqscan = off will actually not mean the planner can't use a
sequential scan for the query if no other alternative exist. In any case
it doesn't mean "please throw an error if you can't do this without a
sequential scan". 

In fact an even more useful option would be to ask the planner to throw
error if the expected cost exceeds a certain threshold...

Cheers,
Csaba.

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