Re: Migration study, step 1: bulk write performanceoptimization

Thanks, will try that. I'll report on the progress later, I have some unit tests to set up first but as soon as that is done I'll go back to optimizing insert performance.

Regards,
Mikael.

-----Original Message-----
From: Jim C. Nasby [mailto:jnasby(at)pervasive(dot)com]
Sent: den 22 mars 2006 13:55
To: Mikael Carneholm
Cc: Simon Riggs; pgsql-performance(at)postgresql(dot)org
Subject: Re: [PERFORM] Migration study, step 1: bulk write
performanceoptimization

On Wed, Mar 22, 2006 at 10:04:49AM +0100, Mikael Carneholm wrote:
> It does ("LOG: checkpoints are occurring too frequently (2 seconds apart)") However, I tried increasing checkpoint_segments to 32 (512Mb) making it checkpoint every 15 second or so, but that gave a more uneven insert rate than with checkpoint_segments=3. Maybe 64 segments (1024Mb) would be a better value? If I set checkpoint_segments to 64, what would a reasonable bgwriter setup be? I still need to improve my understanding of the relations between checkpoint_segments <-> shared_buffers <-> bgwriter... :/

Probably the easiest way is to set checkpoint_segments to something like
128 or 256 (or possibly higher), and then make bg_writer more aggressive
by increasing bgwriter_*_maxpages dramatically (maybe start with 200).
You might want to up lru_percent as well, otherwise it will take a
minimum of 20 seconds to fully scan.

Basically, slowly start increasing settings until performance smooths
out.
--
Jim C. Nasby, Sr. Engineering Consultant jnasby(at)pervasive(dot)com
Pervasive Software http://pervasive.com work: 512-231-6117
vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461