Re: How to ENABLE SQL capturing??? - Mailing list pgsql-performance

From Joshua D. Drake
Subject Re: How to ENABLE SQL capturing???
Date
Msg-id 46C083A7.6000408@commandprompt.com
Whole thread Raw
In response to Re: How to ENABLE SQL capturing???  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-performance
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Gregory Stark wrote:
> "Joshua D. Drake" <jd@commandprompt.com> writes:
>
>> If I recall correctly, it is because syslog is blocking.
>
> Are you sure it isn't just that syslog fsyncs its log files after every log
> message?

Nope I am not sure at all ;). Darcy actually found the issue and can
speak better to it, I never use syslog and have always logged direct to
file.

 I don't think the individual syslogs are synchronous but if syslog
> falls behind the buffer will fill and throttle the sender.
>
> If your Postgres data is on the same device as the syslogs those fsyncs will
> probably cause a big slowdown directly on Postgres's I/O as well.
>
> You can turn off the fsyncs in syslog by putting a - before the filename.
>


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