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Re: Terrible performance on wide selects

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Daniel Kalchev <daniel(at)digsys(dot)bg>
Cc: Hannu Krosing <hannu(at)tm(dot)ee>, Dann Corbit <DCorbit(at)connx(dot)com>,Steve Crawford <scrawford(at)pinpointresearch(dot)com>,pgsql-performance(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Terrible performance on wide selects
Date: 2003-01-23 14:50:02
Message-ID: 25738.1043333402@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-performance
Daniel Kalchev <daniel(at)digsys(dot)bg> writes:
> Does this mean, that constructing tables where fixed length fields are 
> 'before' variable lenght fields and 'possibly null' fields might increase 
> performance?

There'd have to be no nulls, period, to get any useful performance
difference --- but yes, in theory putting fixed-length columns before
variable-length ones is a win.

I wouldn't bother going out to rearrange your schemas though ... at
least not before you do some tests to prove that it's worthwhile.

			regards, tom lane

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