Re: Multiple postmasters for one data directory...

Stef <svb(at)ucs(dot)co(dot)za> writes:
> I've managed to make such a database cluster on a separate postmaster,
> and re-linked all the database directories to point to the data directories
> of all the other postmasters.

> Although this workaround seems to be working rather well, I know for one
> thing that it could be disastrous to have two postmasters running on the
> same data directory at the same time, so I'll ensure that that doesn't happen.

> Is what I'm doing VERY bad, and are there more things I'm overlooking?
> Can this setup possibly break everything?

I'm afraid you have already shot yourself in the foot.

The above cannot work because there is no way to share pg_xlog or
pg_clog across database clusters. You have now got transaction numbers
from the "shared" postmaster inserted into the other databases, and when
you go back to separate postmasters you will have corruption. I'm
surprised you do not already see inconsistencies, because if the
"shared" installation was a fresh one then it would probably see most of
the committed transaction numbers of the other databases as being "in
the future".

Get out your backup tapes, because what you have on disk now is just a
pile of inconsistent bits.

regards, tom lane