From: Tom Lane <tgl@sss.pgh.pa.us>
To: Greg Smith <greg@2ndQuadrant.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Query optimization using order by and limit
Date: Wed, 21 Sep 2011 22:09:21 -0400
Message-ID: <6768.1316657361@sss.pgh.pa.us> (raw)
In-Reply-To: <4E7A93F9.1050301@2ndQuadrant.com>
References: <CA+Z27QQDRQ1h_tD1Tm_+T+-cBdt00hLWYRnvXygxLf_JWNTxZQ@mail.gmail.com>
<4E7A93F9.1050301@2ndQuadrant.com>
Greg Smith <greg@2ndQuadrant.com> writes:
> That weird casting can't be helping. I'm not sure if it's your problem
> here, but the constraint exclusion code is pretty picky about matching
> the thing you're looking for against the CHECK constraint, and this is a
> messy one. The bigint conversion in the middle there isn't doing
> anything useful for you anyway; you really should simplify this to just
> look like this:
> firstloadtime >= 129604464000000000::numeric
I have a more aggressive suggestion: change all the numeric(20,0) fields
to bigint. Unless the OP actually needs values wider than 64 bits,
the choice to use numeric is a significant performance penalty for
nothing.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, greg@2ndQuadrant.com
Subject: Re: Query optimization using order by and limit
In-Reply-To: <6768.1316657361@sss.pgh.pa.us>
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