Message-ID: <48C0500A.8020301@enterprisedb.com>
Date: Fri, 05 Sep 2008 00:15:54 +0300
Organization: EnterpriseDB
User-Agent: Mozilla-Thunderbird 2.0.0.14 (X11/20080509)
MIME-Version: 1.0
To: Zdenek Kotala <Zdenek.Kotala@Sun.COM>
CC: PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Prototype: In-place upgrade
References: <48BB10A2.60503@sun.com>
In-Reply-To: <48BB10A2.60503@sun.com>
Content-Type: text/plain; charset=ISO-8859-2; format=flowed
Content-Transfer-Encoding: 7bit
From: Heikki Linnakangas <heikki.linnakangas@enterprisedb.com>

The patch seems to be missing the new htup.c file.

Zdenek Kotala wrote:
> Attached patch is prototype of in-place upgrade as was presented on
> PGCon this year.
> 
> Main idea is to learn postgres to handle different version of page and 
> tuple structures.
> 
> 1) page - Patch contains new page API and all code access page through 
> this API. Functions check page version and return correct data to 
> caller. It is mostly complete now. Only ItemId flags need finish.
> 
> 2) tuple - HeapTuple structure has been extended with t_ver attribute 
> which contains page layout version and direct access to HeapTupleHeader 
> is forbidden. It is possible now only through HeapTuple* functions (see 
> htup.c). (HeapTupleHeader access still stays in a several functions like 
> heap_form_tuple).
> 
> This patch version still does not allow to read old database, but it 
> shows how it should work. Main disadvantage of this approach is 
> performance penalty.
> 
> Please, let me know your opinion about this approach.
> 
> Future work:
> 1) learn WAL to process different tuple structure version
> 2) tuple conversion to new version and put it into executor 
> (ExecStoreTuple)
> 3) multiversion MaxItemSize constant


-- 
   Heikki Linnakangas
   EnterpriseDB   http://www.enterprisedb.com