Re: Hot Standby 0.2.1

Simon Riggs wrote:
> On Wed, 2009-09-23 at 11:13 +0300, Heikki Linnakangas wrote:
>> I note that we don't emit RunningXacts after a shutdown checkpoint. So
>> if recovery starts at a shutdown checkpoint, we don't let read-only
>> backends in until the first online checkpoint. Could we treat a shutdown
>> checkpoint as a snapshot with no transactions running? Or do prepared
>> transactions screw that up?
>
> We could, but I see no requirement for starting HS from a backup taken
> on a shutdown database. It's just another special case to test and since
> we already have significant number of important test cases I'd say add
> this later.

There's also a related issue that if a backend holding
AccessExclusiveLock crashes without writing an abort WAL record, the
lock is never released in the standby. We handle the expiration of xids
at replay of running-xacts records, but AFAICS we don't do that for locks.

It shouldn't be much code to clear those states at shutdown checkpoint,
just a few lines to call the right functions methinks.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com