Re: Querry and SMP mechine

On Sun, Aug 07, 2005 at 02:15:50PM +0300, Michael Ben-Nes wrote:
> >Yep, PostgreSQL uses a single backend for each client, so if you want
> >to use all four processors, you need to be running four queries
> >simultaneously...
> >
> >
> You mean select 1, select 2 & sleect 3 will run on the same cpu becouse
> they submited from the same PSQL session ?
> Or each select will be run in turn on the most idle cpu ?

No, they are run in the same single process and run on one cpu. The OS
can ofcourse shift it to whichever CPU it thinks is most appropriate.
It can shift it in the middle of a query too, but that's not up to
PostgreSQL.

> Is this true for all the other OS or just for Linux ? (Bsd, solaris... )

A single client uses a single CPU at a time, but it's not tied to that
particular CPU. That applies to all supported platforms...

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.