Re: Streaming Replication patch for CommitFest 2009-09

Greg Smith wrote:
> Putting on my DBA hat for a minute, the first question I see people
> asking is "how do I measure how far behind the slaves are?". Presumably
> you can get that out of pg_controldata; my first question is whether
> that's complete enough information? If not, what else should be monitored?
>
> I don't think running that program going to fly for a production quality
> integrated replication setup though. The UI admins are going to want
> would allow querying this easily via a standard database query. Most
> monitoring systems can issue psql queries but not necessarily run a
> remote binary. I think that parts of pg_controldata needs to get
> exposed via some number of built-in UDFs instead, and whatever new
> internal state makes sense too. I could help out writing those, if
> someone more familiar with the replication internals can help me nail
> down a spec on what to watch.

Yep, assuming for a moment that hot standby goes into 8.5, status
functions that return such information is the natural interface. It
should be trivial to write them as soon as hot standby and streaming
replication are in place.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com