Re: Warm/hot backup server question

"Faber J. Fedor" <faber@linuxnj.com> writes:
> I've been given the job of creating a hot/warm backup server
> for a live Postgresql server.  The problem is two-fold: 1) it's version
> 7.4.9 and an upgrade is not feasible at this time and b) there are
> multiple instances of postgresql running on the box; not multiple
> databases, multiple *servers*, each listening on a different port (it
> was a business requirement from what I've been told).

If they won't let you update to 7.4.18 (the current release in that
branch), you would be best advised to resign at once, before you get
blamed for the train wreck that is inevitably in this system's future.
7.4.9 is two years old, and I count at least six fixes since then for
data-loss bugs of the *will*-bite-you-eventually type; plus a couple
more that you might be at risk for depending on which features you use.
Also, the choice to run separate servers sounds a whole lot like they
are serving clients that they don't trust 100%, which means there are
also half a dozen security fixes that they should be worried about.

> Can 7.4 do the same magic as 8.2 wrt to WAL?

No.  Slony is your best bet --- not least because it may simplify a live
upgrade to a newer version.

            regards, tom lane