Re: Running Multiple Postmasters

On Thu, 26 Feb 2004, John Allgood wrote:

> Hello
>
> I am building a server to run 9 databases. Can I run a seperate
> postmaster for each of the 9 databases. I would be setting the port
> number to a different value for each db of course. The reason I wish to
> do this is so that I can install about three databases on a seperate
> disk and put the other on seperate disk as well.

Up to here, there's no need for seperate postmasters, as you can easily
install different databases onto different disk spaces.

If this is your only reason, look into:

http://www.postgresql.org/docs/7.4/static/manage-ag-alternate-locs.html

Plus it gives you the advantage that you have one database cluster to
manage and your tuning only needs to take into account a server handling
one database.

That said, it's pretty easy to put multiple instances on one machine.

The way I do it, is to create a seperate account for each instance to run
in, so that by looking at the prompt I know which database I'm
administering, and no matter how much I might fat finger things, if I'm
logged in as pgsql01 and try to delete the files for pgsql02 I can't do
it, I don't have permission to.

Then you just have a line like this in rc.local for each database to get
it started.

su - pgsql1 -c -- 'pg_ctl start -l $PGDATA/pgsql.log'

I'm not sure anymore (it's been a while since I did it last) if you have
to include a port number anywhere in there. I think the pg_ctl /
postgresql.conf file handle all that though.