Wierd quirk of HS/SR, probably not fixable

Hackers,

Here's a way to trap yourself:

(1) Set up an HS/SR master
(2) pg_start_backup on the master
(3) clone the master to 1 or more slaves
(4) Fast shutdown the master (without pg_stop_backup)
(5) Restart the master
(6) Bring up the slaves

Result: the slaves will come up fine in recovery mode.  However, they
will never switch over to HS mode or start SR.  You will not be able to
pg_stop_backup() on the master.  At this point, you have no option but
to shut down the slaves and re-clone.

The only reason why this is somewhat problematic for users is that you
will not get any messages from the master or the slaves to indicate why
they won't switch modes.  So I can imagine someone wasting a lot of time
troubleshooting the wrong problems.

Suggested resolution: I don't think there's and logical "fix" for this
case; it should just be added to the docs as a failure/troubleshooting
condition.

--                                  -- Josh Berkus                                    PostgreSQL Experts Inc.                                    http://www.pgexperts.com