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Re: Reduce heap tuple header size

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Jan Wieck <JanWieck(at)Yahoo(dot)com>
Cc: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>,Manfred Koizar <mkoi-pg(at)aon(dot)at>, pgsql-patches(at)postgresql(dot)org
Subject: Re: Reduce heap tuple header size
Date: 2002-06-21 13:44:36
Message-ID: 19025.1024667076@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
Jan Wieck <JanWieck(at)Yahoo(dot)com> writes:
> Do we have any hard numbers on that? Is it just access to the header
> fields, or do we loose the offset cacheability of all fixed size fields
> at the beginning of a row? In the latter case count me into the
> slowness-believer camp.

I don't believe the patch would have made the header variable size,
only changed what the fixed size is.  The slowdown I was worried about
was just a matter of a couple extra tests and branches in the tqual.c
routines; which would be negligible if they weren't such hotspots.

			regards, tom lane

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