From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
---|---|
To: | "Jim C(dot) Nasby" <jnasby(at)pervasive(dot)com> |
Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Wes <wespvp(at)syntegra(dot)com>, Zeugswetter Andreas DCP SD <ZeugswetterA(at)spardat(dot)at>, pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Catalog Access (was: [GENERAL] Concurrency problem building indexes) |
Date: | 2006-04-25 17:40:24 |
Message-ID: | 20060425174024.GD20309@svana.org |
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Lists: | pgsql-hackers |
On Tue, Apr 25, 2006 at 12:25:35PM -0500, Jim C. Nasby wrote:
> Is there anything in comments/docs/list archives about why catalog
> access uses a bunch of 'magic' instead of treating catalog tables the
> same as every other table? I realize that ultimately you have to
> bootstrap somehow (kinda hard to read from pg_class if the info needed
> to do so is in pg_class), but perhaps switching over to the regular
> access methods after the system is up would be worth-while.
I don't know if it's explicitly documented, but here's one mail that
describes some of the issues:
http://www.thelinuxreview.com/pgsql-hackers/2005-03/msg00840.php
I think the basic problem is that DDL can't really work within a
transaction. If I do an ALTER TABLE, some of these changes need to show
up to concurrent transactions (maybe creating a unique index?).
I think it's like Tom says in that email, it could be done, but the
cost/benefit ratio isn't very good...
Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> From each according to his ability. To each according to his ability to litigate.
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