Subject: Re: checkpoints, proper config
To: Alvaro Herrera <alvherre@2ndquadrant.com>
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Cc: pgsql-performance@postgresql.org
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
Message-ID: <566A24DD.8020106@2ndquadrant.com>
Date: Fri, 11 Dec 2015 02:20:29 +0100
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On 12/10/2015 11:45 PM, Alvaro Herrera wrote:
> Tomas Vondra wrote:
>
>> Also, I don't think it makes much sense to set
>>
>>     (checkpoint_warning > checkpoint_timeout)
>>
>> as it kinda defeats the whole purpose of the warning.
>
> I agree, but actually, what is the sense of checkpoint_warning?  I think
> it was useful back when we didn't have log_checkpoints, but now that we
> have detailed checkpoint logging I think it's pretty much useless noise.
>

Not entirely. The WARNING only triggers when you get below the 30s (or 
whatever value is set in the config) and explicitly warns you about 
doing checkpoints too often. log_checkpoints=on logs all checkpoints and 
you have to do further analysis on the data (and it's just LOG).


--
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services


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