Re: max_standby_delay considered harmful

Josh Berkus wrote:
> Having built-in replication in PostgreSQL was supposed to give the *majority* of users a *simple*
> option for 2-server failover, not cater only to the high end.

If that's your criteria, 9.0 has already failed that goal. Just the
fact that you have to make your own base backup and manage that whole
area alone excludes "simple" as a goal anyone can claim 9.0 meets with a
straight face, long before you get to the mechanics of how HS handles
query cancellation. The new replication oriented features are
functional, but neither are close to simple yet. Based on the
complication level of replication in other database products, I wouldn't
put money on that even being possible. You can make a simpler path the
default one, but the minute you want to support more than one use case
the complexity involved in setting up replication explodes.

Anyway, I have no idea where the idea that recommending time
synchronization is a somehow a "high end" requirement, given that every
OS I'm aware of makes that trivial nowadays. Slave servers that drift
too far away from the master time are going to cause all sorts of
problems for user apps too. Any app that gauges how long ago something
happened by comparing a database timestamp with now() is going to give
misleading results for example, and I know I see those all the time.

--
Greg Smith 2ndQuadrant US Baltimore, MD
PostgreSQL Training, Services and Support
greg(at)2ndQuadrant(dot)com www.2ndQuadrant.us