check_postgres.pl (http://bucardo.org/wiki/Check_postgres) is a great tool for giving you an early heads up that replication lag is getting behind.  Used in conjunction with something like nagios, it will pretty much let you know as soon as things start going wrong.  In my experience, once you get to that point where replication falls a day behind it's becomes progressively harder to fix.  Knowing that something broke five minutes ago usually makes it much easier to track down.

Brian Hirt
bhirt at me.com



On Nov 13, 2010, at 12:48 AM, Aleksey Tsalolikhin wrote:

> Thank you for your kind replies. sl_status table in the slony schema
> shows st_last_event and st_last_received are growing.
> 
> No errors in the Slony or Postgres log files on the master nor the slave.
> 
> I've shut down the slave and master; dropped the DB on the slave; and
> recreated the replication set.  It's copying across now (23 GB).
> We'll see how it holds up after the resync.
> 
> Thanks!
> Aleksey
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