Thread: Running both PG 8 and PG 9

Hi all,

I just installed PG 9 on my Macbook (enterprisedb) just to start playing
around with it. My Postgres 8.4 installation won't start now anymore, it
is complaining about shared memory already being in use.

Is it even possible to run PG 8 and PG 9 side by side? I was under the
impression this was possible provided they listen on different ports?

Thanks,

Bastiaan Olij

Bastiaan Olij <bastiaan@basenlily.me> writes:
> I just installed PG 9 on my Macbook (enterprisedb) just to start playing
> around with it. My Postgres 8.4 installation won't start now anymore, it
> is complaining about shared memory already being in use.

> Is it even possible to run PG 8 and PG 9 side by side? I was under the
> impression this was possible provided they listen on different ports?

Yes, it is, but the default SHMMAX on OS X is too small to allow
starting two postmasters at once.  Crank up the shmem settings (see
our manual for details) and you should be fine.

            regards, tom lane