Re: PG Logging is Slow

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Theo Galanakis <Theo(dot)Galanakis(at)lonelyplanet(dot)com(dot)au>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: PG Logging is Slow
Date: 2004-12-20 04:31:24
Message-ID: 200412200431.iBK4VOd03148@candle.pha.pa.us
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Theo Galanakis wrote:
> Under postgres 7.3 logging is incredibly slow!
>
> I have applied the following settings:
>
> syslog = 2
> syslog_facility = 'LOCAL0'
> syslog_ident = 'postgres'
>
> log_connections = true
> log_duration = true
> log_pid = true
> log_statement = true
> log_timestamp = true
>
> This severely impacted the performance of our production system, a search
> page which took 1-3 seconds now takes over 30, is this normal?
>
> I need to get some performance indicators from our production db, however I
> cant turn on logging with such performance degradation.

Linux syslog has this bad behavior of fsync'ing all log writes. See the
syslog manual page for a way to turn off the fsync.

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