Re: Hot Standby 0.2.1

Heikki Linnakangas wrote:
> 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.

Ah, scratch that, I now see that we do call
XactClearRecoveryTransactions() when we see a shutdown checkpoint, which
clears all recovery locks. But doesn't that prematurely clear all locks
belonging to prepared transactions as well?

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