2 instances of postmaster with different data directories

surabhi.ahuja wrote:

Hi,

I am going to integrate my dtabase into a system. That system also
has another database and uses postgres.

However they have their own data directory and start postmaster by
specifying that.

I have seen that it is possible to run multiple postmasters on
multiple ports by specifying diffrent data directories.

But we are still to decide if we should go with the above
approach....or is it better to have just one data directory and one
instance of postmaster on the default port.

Two instances will be less efficient:
- two separate areas of shared-memory
- two caches
- possible I/O competition (particularly with WAL I'd expect)
- twice as many upgrades needed when patches are released
but will allow:
- two different versions of PostgreSQL
- separate user lists

Does that help?
--
Richard Huxton
Archonet Ltd