Re: Scaling postgres

On Sat, 13 Apr 2002 17:00:19 -0500
"Steve Lane" <slane@fmpro.com> wrote:
> On the front end, as I understand it (I know this is not really
> Postgres-specific), with Apache and mod_php I need one process per
> concurrent user. Anyone care to speculate how many concurrent users I could
> get on a single box? I really don't know what's reasonable to expect.

For the front-end, it totally depends on the hardware you're using,
the OS you're running this on, and the design/performance requirements
of your application. For example, a good caching layer could easily
improve performance by 100% or more.

> On the back end, is there any direct relationship between the number of open
> client connections and the number of processes used?

Yes, there is 1 postgres process per database connection. Whether
you create 1 database connection per client would depend on how you
design your application.

> My question again would be, is it at all reasonable to think that
> the postgres back end, running on a single box, could handle 800-1200
> concurrent users?

Not really sure. By "concurrent users", do you mean "executing queries
at any given time", or "logged in" (so that perhaps 10% of those will
actually be hitting the DB)?

> Is it a matter of running multiple postmasters?

If you mean running multiple postmasters on a single machine, that
is unlikely to help.

> If I can't get all those users on one back-end box, how do I distribute them
> across multiple servers but have them all access the same data store?

There might be support for replication in 7.3; until then, there
are some projects like erServer you can take a look at.

Cheers,

Neil

--
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC