Re: new --maintenance-db options

Robert Haas <robertmhaas@gmail.com> writes:
> From pg_upgrade's perspective, it would
> be nice to have a flag that starts the server in some mode where
> nobody but pg_upgrade can connect to it and all connections are
> automatically allowed, but it's not exactly clear how to implement
> "nobody but pg_upgrade can connect to it".

The implementation I've wanted to see for some time is that you can
start a standalone backend, but it speaks FE/BE protocol to its caller
(preferably over pipes, so that there is no issue whatsoever of where
you can securely put a socket or anything like that).  Making that
happen might be a bit too much work if pg_upgrade were the only use
case, but there are a lot of people who would like to use PG as an
embedded database, and this might be close enough for such use-cases.

However, that has got little to do with whether --maintenance-db is a
worthwhile thing or not, because that's about external client-side
tools, not pg_upgrade.
        regards, tom lane