Re: Support for N synchronous standby servers - take 2

On Fri, Feb 12, 2016 at 2:56 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Feb 5, 2016 at 3:36 AM, Michael Paquier
> <michael(dot)paquier(at)gmail(dot)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.

I was referring to a catalog view that parses the information related
to groups of s_s_names in a flattened way to show each group sync
status. Perhaps my words should have been clearer.
--
Michael