Subject: Re: formula about the number of WAL files
From: Simon Riggs <simon@2ndQuadrant.com>
To: Fujii Masao <masao.fujii@gmail.com>
Cc: pgsql-docs <pgsql-docs@postgresql.org>
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Date: Fri, 15 Oct 2010 14:48:57 +0100
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On Fri, 2010-10-15 at 19:44 +0900, Fujii Masao wrote:

> As the result of the above, the maximum number of WAL files in
> pg_xlog is
> 
>     (2 + checkpoint_completion_target) * checkpoint_segments + 1
> 
>     or
> 
>     wal_keep_segments + checkpoint_segments + 1
> 
> So the original description seems to be correct. Am I missing
> something?

After some thought, I agree.

> # My previous proposal is definitely wrong. Sorry for noise.

I'd say the definition of wal_keep_segments isn't good, which is what is
causing the problem here. Will sort that out another day.

I will update the current code with some comments, so this doesn't
happen again. Will do this on Tuesday now, no time left here.

-- 
 Simon Riggs           www.2ndQuadrant.com
 PostgreSQL Development, 24x7 Support, Training and Services