Re: Streaming replication status and fail over questions

On Fri, 2011-06-03 at 11:07 -0700, Michael Holt wrote:
> I'm investigating moving from slony to streaming replication as we
> plan some upgrades from 8.x versions of postgres to 9. I've managed to
> get it working but there's a couple questions I've been unable to find
> answers to so far.
>
> 1) I've seen things about using pg_current_xlog_location(),
> pg_last_xlog_replay_location(), pg_last_xlog_receive_location() to
> check replication status, but how can this tell me either the time lag
> or actual query lag?

It can't.

> Do I need to wait for 9.1 and it's replication monitoring features?
>

It will only give you time lag (and some nice views, but no query lag).

> 2) If I have a master to multi-slave setup and need to fail over, is
> there anyway for slaves to detect the new master?

Automatically, no.

> Without this it seems like fail over could be pretty messy.
>

Failover isn't messy. Switchover, in the other hand, is pretty
difficult.

> 3) Finally just wanted to confirm that SR allows only for replication
> of an entire server.
>

Yes.

--
Guillaume
http://blog.guillaume.lelarge.info
http://www.dalibo.com