Received: from localhost (unknown [200.46.204.182])
	by postgresql.org (Postfix) with ESMTP id 4055D2E00DB
	for <pgsql-sql-postgresql.org@postgresql.org>;
	Mon,  7 Jan 2008 10:10:01 -0400 (AST)
Received: from postgresql.org ([200.46.204.71])
	by localhost (mx1.hub.org [200.46.204.182]) (amavisd-maia, port 10024)
	with ESMTP id 17576-01 for <pgsql-sql-postgresql.org@postgresql.org>;
	Mon,  7 Jan 2008 10:09:49 -0400 (AST)
Received: from fk-out-0910.google.com (fk-out-0910.google.com
 [209.85.128.190])
	by postgresql.org (Postfix) with ESMTP id E8A362E2F64
	for <pgsql-sql@postgresql.org>; Mon,  7 Jan 2008 10:09:54 -0400 (AST)
Received: by fk-out-0910.google.com with SMTP id b27so9828719fka.3
	for <pgsql-sql@postgresql.org>; Mon, 07 Jan 2008 06:09:52 -0800 (PST)
Received: by 10.82.158.12 with SMTP id g12mr9034092bue.18.1199714990143;
	Mon, 07 Jan 2008 06:09:50 -0800 (PST)
Received: from ?192.168.1.65? ( [84.81.213.205])
	by mx.google.com with ESMTPS id f13sm9853555gvd.18.2008.01.07.06.09.47
	(version=SSLv3 cipher=RC4-MD5); Mon, 07 Jan 2008 06:09:47 -0800 (PST)
Subject: Re: reading WAL files in python
From: "C." =?ISO-8859-1?Q?Bergstr=F6m?= <cbergstrom@netsyncro.com>
To: pgsql-sql@postgresql.org
In-Reply-To: <478226FB.6030306@fmed.uba.ar>
References: <478226FB.6030306@fmed.uba.ar>
Content-Type: text/plain
Date: Mon, 07 Jan 2008 15:05:28 +0100
Message-Id: <1199714728.11354.309.camel@chaos>
Mime-Version: 1.0
X-Mailer: Evolution 2.12.2 
Content-Transfer-Encoding: 7bit
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Archive-Number: 200801/23
X-Sequence-Number: 29877


On Mon, 2008-01-07 at 10:19 -0300, Gerardo Herzig wrote:
> Hi all. Im having some fun trying to write my own replication system 
> using python. I will use the postgres own WAL archiving to write the 
> files,  then my app will read them and do some stuff. As im not a C 
> programmer, im stuck in the mission of reading the binary files.
> 
> I guess im needing to know the internals of how wals archives are, how 
> big the buffer has to be, in order to have a complete sql command.
> 
> Can someone point some advice?
> I was trying to understad src/backend/access/transam/xlog.c, but seems 
> too difficult to me :(
> 

imho you can save yourself a lot of time by taking a look at skytools[1]
as it may be more along the lines of what you're trying to accomplish
anyway.

Cheers,

./C

[1] https://developer.skype.com/SkypeGarage/DbProjects/SkyTools