Given 2 nodes A and B in a slony replication cluster, with A as the
provider for a single set, if at some point I need to failover to B,
what are my options for eventually returning A to provider status? Once
we've failed over to B, we eventually want to get A back to being the
main guy.

It looks like the first step is to set up a fresh schema in A, and
subscribe it to B. I thought at first I would want to populate it first
with a pg_dump from B, but I see that the ENABLE_SUBSCRIPTION logic
truncates the target table before copying to it. 

Will simply subscribing the new A to B result in all existing B data
geting copied over? If so, how does this compare performance-wise with
using pg_dump? (I realize this comparison is apples vs. oranges, and
really a comparision between table copy and pg_dump, hence not
slony-specific, but if anybody has any experience with this I'd
appreciate hearing about it).

Assuming I'm able to fully load A with data from B, is it possible to
switch them such that A becomes the provider and B goes back to receive
mode? This is complicated if updates are continuing to B, of course, but
I wonder if it is possible at all.

Finally, what query would I execute against 2 nodes to know if their
data is in sync (at that moment)?

Thanks in advance for any answers/corrections to any of my numerous
questions!

-  DAP
====================================================== 
David Parker    Tazz Networks    (401) 709-5130