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
