Re: Confused by 'timing' results

Just to give an update, changing pg_log to a different drive that is write cache
enabled (and to further make it fast, kept it data=writeback), helped quite a
bit.

The average time for several clients hitting concurrently was 15ms each for
east-coast as well as west-coast clients. Still some impact of network is still
at play as the time taken directly on database server was much less at 10ms.

Not logging at all is still better (the time on database with
log_min_duration=-1, is 5.4ms) but putting the log on a different drive adds
only minimal overhead and ability to measure query time reasonably by discarding
most of the network variance.

________________________________
From: A J <s5aly(at)yahoo(dot)com>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>; Scott Marlowe
<scott(dot)marlowe(at)gmail(dot)com>; pgsql-admin(at)postgresql(dot)org
Sent: Thu, September 2, 2010 3:21:24 PM
Subject: Re: [ADMIN] Confused by 'timing' results

PostgreSQL 8.4
CentoOS 5.5
I have got WCE=0, on the drive that mounts the data directory with all its
subdirectory (including pg_log)

Maybe I should try to mount pg_log to a different drive and have write cache
enabled on that one.

________________________________
From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: A J <s5aly(at)yahoo(dot)com>
Cc: Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>; Scott Marlowe
<scott(dot)marlowe(at)gmail(dot)com>; pgsql-admin(at)postgresql(dot)org
Sent: Thu, September 2, 2010 3:17:42 PM
Subject: Re: [ADMIN] Confused by 'timing' results

A J <s5aly(at)yahoo(dot)com> writes:
> Do you think changing log_destination to syslog may make a difference

It's worth trying alternatives anyway. It is odd that you are seeing
such a slowdown when using the collector --- many people push very high
log volumes through the collector without problems. What PG version is
this exactly, and on what platform?

regards, tom lane