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>
In-Reply-To: <AANLkTik0sqru9oMZeTL4vnFkAaDYZB=-Meonv9gnroiu@mail.gmail.com>
References: <AANLkTik0sqru9oMZeTL4vnFkAaDYZB=-Meonv9gnroiu@mail.gmail.com>
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Date: Fri, 15 Oct 2010 10:19:56 +0100
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On Thu, 2010-10-14 at 12:00 +0900, Fujii Masao wrote:
> ----------------
> 29.4. WAL Configuration
> 
> There will always be at least one WAL segment file, and will normally not
> be more than (2 + checkpoint_completion_target) * checkpoint_segments + 1
> or checkpoint_segments + wal_keep_segments + 1 files.
> ----------------
> 
> The above formula is wrong. The correct is
> 
>     (2 + checkpoint_completion_target) * checkpoint_segments +
> wal_keep_segments + 1
> 
> The attached patch fixes this fault.

The current docs are wrong, but your re-definition doesn't match the
actual code in CreateCheckPoint(). 

I've updated the docs to reflect how the code behaves.

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