Re: Support for N synchronous standby servers - take 2

On Fri, Feb 5, 2016 at 3:36 AM, Michael Paquier
<michael.paquier@gmail.com> wrote:
> So, here are some thoughts to make that more user-friendly. I think
> that the critical issue here is to properly flatten the meta data in
> the custom language and represent it properly in a new catalog,
> without messing up too much with the existing pg_stat_replication that
> people are now used to for 5 releases since 9.0.

Putting the metadata in a catalog doesn't seem great because that only
can ever work on the master.  Maybe there's no need to configure this
on the slaves and therefore it's OK, but I feel nervous about putting
cluster configuration in catalogs.  Another reason for that is that if
synchronous replication is broken, then you need a way to change the
catalog, which involves committing a write transaction; there's a
danger that your efforts to do this will be tripped up by the broken
synchronous replication configuration.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company