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Re: [PATCHES] Reduce heap tuple header size

From: Curt Sampson <cjs(at)cynic(dot)net>
To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
Cc: Manfred Koizar <mkoi-pg(at)aon(dot)at>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>,PostgreSQL-development <pgsql-hackers(at)postgreSQL(dot)org>
Subject: Re: [PATCHES] Reduce heap tuple header size
Date: 2002-07-01 02:50:14
Message-ID: Pine.NEB.4.43.0207011145400.408-100000@angelic.cynic.net (view raw or flat)
Thread:
Lists: pgsql-hackerspgsql-patches
On Fri, 28 Jun 2002, Bruce Momjian wrote:

> OK, we need to vote on this patch.  It reduces the tuple header by 4
> bytes (11% decrease).
>
> If we apply it, we will not be able to easily use pg_upgrade for 7.3
> because the on-disk table format will change.
>
> Votes are:
>
> 1) Apply it now
> 2) Wait until August and see if any other table format changes are made.
> 3) Delay patch until we have other table format changes.

I would tend to say "apply it now" so that we can get more testing
of it.

It would also be good to see how else we could save space in the
header, e.g., by not having an empty OID field when a table is
created without OIDs. (That would double the space savings.)

I tend to use ID cross reference tables quite a lot, and these tend to
have a lot of rows in them. (E.g., group table has group ID; user table
has user-id; a group-id + user-id table determines which users are in
which groups. In one project a couple of years ago, such a table was 85
million rows.) These types of tables are typically 8 bytes of data and
40 or so bytes of overhead. Ouch!

cjs
-- 
Curt Sampson  <cjs(at)cynic(dot)net>   +81 90 7737 2974   http://www.netbsd.org
    Don't you know, in this new Dark Age, we're all light.  --XTC




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