This is looking really neat now, making async replication really solid
first before even trying to move on to sync is the right way to go here
IMHO. I just cleaned up the docs on the Wiki page, when this patch is
closer to being committed I officially volunteer to do the same on the
internal SGML docs; someone should nudge me when the patch is at that
point if I don't take care of it before then.
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.
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* Greg Smith gsmith@gregsmith.com http://www.gregsmith.com Baltimore, MD