On Wed, Aug 26, 2009 at 9:14 PM, Han He<hansfly at gmail.com> wrote:
> Thanks for your kind reply.
> Actually what I mean 'atomic' is that, for example, if on parent, update
> table A and table B, then slony trigger replication on slave node, update
> table A succeed, however update table B fail, can slony rollback the table
> A?

rollback table A on the master or the slave?

With Slony, the following sequence happens when table A and table B
are in the same replication set:

On master:
  begin;
  update A set ....;
  update B set ...;
  commit;

[time passes]

On slave:
  begin;
  update A set ...;
  update B set ...;
  commit;

The updates on the slave do not start until after the transaction on
the master has committed.

So if you want the updates on the master be rolled back if the updates
on the slave fail, you cannot do that with an asynchronous replication
system like Slony. You need a synchronous replication system like
pgpool.

If you mean will the table A update on the slave be rolled back, that
is what happens. If you do not see this behavior, then either the
tables are in separate replication sets, or the updates on the master
were not atomic (perhaps the client was in auto commit mode?).


-- 
Stuart Bishop <stuart at stuartbishop.net>
http://www.stuartbishop.net/