Re: 8.3 synchronous_commit

On Mon, 21 Jan 2008, Hannes Dorbath wrote:

> pgbench -i -s 10 -U pgsql -d bench && pgbench -t 1000 -c 100 -U pgsql -d
> bench

pgbench doesn't handle 100 clients at once very well on the same box as
the server, unless you have a pretty serious system. The pgbench program
itself has a single process model that doesn't handle the CFQ round-robin
very well at all. On top of that, the database scale should be bigger
than the number of clients or everybody just fights for the branches
table. You said you tried with a larger scale as well, but that also
vastly increases the size of the database which shifts to a completely
different set of bottlenecks. See
http://www.westnet.com/~gsmith/content/postgresql/pgbench-scaling.htm for
more on this.

Try something more in the range of 4 clients/CPU and set the scale to
closer to twice that (so with a dual-core system you might do 8 clients
and a scale of 16). If you really want to simulate a large number of
clients, do that on another system and connect to the server remotely.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD