Re: PG Logging is Slow

From: Bruce Momjian
Subject: Re: PG Logging is Slow
Date: ,
Msg-id: 200412200431.iBK4VOd03148@candle.pha.pa.us
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In response to: PG Logging is Slow  (Theo Galanakis)
List: pgsql-performance

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PG Logging is Slow  (Theo Galanakis, )
 Re: PG Logging is Slow  (Bruce Momjian, )
 Re: PG Logging is Slow  (Grega Bremec, )
 Re: PG Logging is Slow  (Michael Adler, )
 Re: PG Logging is Slow  (Theo Galanakis, )
  Re: PG Logging is Slow  (Alexander Borkowski, )
 Re: PG Logging is Slow  (Theo Galanakis, )

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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