Re: Synchronous Standalone Master Redoux

On Thu, Jul 12, 2012 at 08:21:08AM -0500, Shaun Thomas wrote:
> >But, putting that aside, why not write a piece of middleware that
> >does precisely this, or whatever you want? It can live on the same
> >machine as Postgres and ack synchronous commit when nobody is home,
> >and notify (e.g. page) you in the most precise way you want if nobody
> >is home "for a while".
> 
> You're right that there are lots of ways to kinda get this ability,
> they're just not mature enough or capable enough to really matter.
> Tailing the log to watch for secondary disconnect is too slow. Monit
> or Nagios style checks are too slow and unreliable. A custom-built
> middle-layer (a master-slave plugin for Pacemaker, for example) is
> too slow. All of these would rely on some kind of check interval.
> Set that too high, and we get 10,000xn missed transactions for n
> seconds. Too low, and we'd increase the likelihood of false
> positives and unnecessary detachments.

Well, the problem also exists if add it as an internal database feature
--- how long do we wait to consider the standby dead, how do we inform
administrators, etc.

I don't think anyone says the feature is useless, but is isn't going to
be a simple boolean either.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com
 + It's impossible for everything to be true. +