Re: Feature Request: pg_replication_master()

Josh Berkus <josh@agliodbs.com> writes:
>> What the patch doesn't change is the requirement to have a file that
>> causes the server to place itself into archive recovery. So there is
>> no more recovery.conf and instead we have a file called
>> recovery.trigger instead.

> Requiring a file in order to make a server a replica is what we should
> be trying to get away from.  It should be possible to configure a server
> as a replica by setting a GUC in PostgreSQL.conf (before first startup,
> obviously).

I'm not entirely convinced about that, because if we do it like that, we
will *never*, *ever* be able to store GUC settings except in a flat,
editable textfile.  Now, that's fine by me personally, but there seem to
be a lot of people around here with ambitions to bury those settings in
not-so-editable places.  Including you, to judge by your next sentence:

> Naturally, this then links in with SET PERSISTENT or
> however we're calling it these days in order to take a server out of
> replica mode.

People are going to want to be able to push a server into, and possibly
out of, replica mode without necessarily having the server up at the
time.  So I'm not real convinced that we want that flag to be a GUC.
A trigger file is a lot easier to manipulate from places like shell
scripts.
        regards, tom lane