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Re: WAL file utilization question

From: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
To: Keaton Adams <kadams(at)mxlogic(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: WAL file utilization question
Date: 2007-05-16 16:35:20
Message-ID: 20070516163520.GZ4582@alvh.no-ip.org (view raw or flat)
Thread:
Lists: pgsql-admin
Keaton Adams wrote:

> Even with full_page_writes set to false and checkpoints taking place
> every 60 seconds or so, the amount of WAL log data generated per minute
> seems to be significant.

Stop right there.  Having checkpoints every 60 seconds is insane.  Did
you look into increasing checkpoint_segments a lot?

> So my question is this: If I kick off a transaction that loads records
> with a size of 100 bytes, does the insert for that record take 100 bytes
> in the WAL file, or is the data archived in the WAL log in page size
> (8k) portions?

Vicinity of 100 bytes, except right after checkpoints as you noted.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.

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