From: | Ron <rjpeace(at)earthlink(dot)net> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: New to PostgreSQL, performance considerations |
Date: | 2006-12-12 17:56:28 |
Message-ID: | E1GuBri-00061e-Fi@elasmtp-galgo.atl.sa.earthlink.net |
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Thread: | |
Lists: | pgsql-performance |
At 10:47 AM 12/12/2006, Tom Lane wrote:
>It's notoriously hard to get repeatable numbers out of pgbench :-(
That's not a good characteristic in bench marking SW...
Does the ODSL stuff have an easier time getting reproducible results?
>A couple of tips:
> * don't put any faith in short runs. I usually use -t 1000
> plus -c whatever.
> * make sure you loaded the database (pgbench -i) with a
> scale factor (-s) at least equal to the maximum -c you want to test.
> Otherwise you're mostly measuring update contention.
> * pay attention to when checkpoints occur. You probably
> need to increase checkpoint_segments if you want pgbench not to be
> checkpoint-bound.
This all looks very useful. Can you give some guidance as to what
checkpoint_segments should be increased to? Do the values you are
running pgbench with suggest what value checkpoint_segments should be?
Ron Peacetree
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