On Wed, Nov 02, 2005 at 10:44:36AM -0500, Christopher Browne wrote:
> If the possible problem is "runaway bad query," then I suppose that
> having 50 databases would buy *some* protection, although the cost of
> 100 slons x several backends per slon shows that the pricetag is
> prohibitively high.

What protection?  Assuming the credential-separated schemas that Rod
proposed, a runaway query is no more damaging to the other schemas
than it is in the separate database case.  Unless you're thinking of
separate back ends as well, at which point I suggest your
provisioning problem on 100 back ends neither begins nor ends at the
number of processes required to support replication.  

> But if the load on the system is low enough that you can afford to have
> 50 databases hosted on one postmaster, then it seems improbable that
> load balancing is one of the goals.  I think, for that scenario, I'd
> point to PITR as being "the answer."  Slony-I isn't intended to be the
> answer to every problem.

I don't think the management tools are anything like sophisiticated
enough right now to make PITR a solution to recovering one database
among many on a single back end.  Indeed, my impression is that we're
trying to solve the case where one of these "databases" (either
database or SQL schema) has problems and the rest don't.  But PITR
works on xlog, which means it works on the whole back end.   You have
to do a backend shutdown to recover, according to the 8.0 docs.

A

-- 
Andrew Sullivan  | ajs at crankycanuck.ca
I remember when computers were frustrating because they *did* exactly what 
you told them to.  That actually seems sort of quaint now.
		--J.D. Baldwin