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From: PFC <lists@peufeu.com>
To: pgsql-hackers@postgresql.org
Subject: Re: [PERFORM] Big IN() clauses etc : feature proposal
Date: Wed, 10 May 2006 21:27:21 +0200
Message-ID: <op.s9cobvzhcigqcu@apollo13> (raw)
In-Reply-To: <20060510190617.GP99570@pervasive.com>
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	<28288.1147111196@sss.pgh.pa.us>
	<op.s89zl30wcigqcu@apollo13>
	<20060509105214.P90693@vesihiisi.cksoft.de>
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	<20060509113337.M90693@vesihiisi.cksoft.de>
	<op.s893vzcpcigqcu@apollo13>
	<20060509103632.GD29652@svana.org>
	<op.s897j60qcigqcu@apollo13>
	<20060510190617.GP99570@pervasive.com>



> Have you tried getting a profile of what exactly PostgreSQL is doing
> that takes so long when creating a temp table?

	Nope, I'm not proficient in the use of these tools (I stopped using C  
some time ago).

> BTW, I suspect catalogs might be the answer,

	Probably, because :

	- Temp tables don't use fsync (I hope)
	- Catalogs do
	- fsync=off makes COMMIT fast
	- fsync=on makes COMMIT slow
	- fsync=on and using ANALYZE makes COMMIT slower (more updates to the  
catalogs I guess)

> which is why Oracle has you
> define a temp table once (which does all the work of putting it in the
> catalog) and then you just use it accordingly in each individual
> session.

	Interesting (except for the ANALYZE bit...)

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