Heikki Linnakangas wrote: > The problem becomes a lot easier if we accept that it's OK to have a > lock included in the running-xacts snapshot and also appear in a > XLOG_RELATION_LOCK record later. The standby should handle that > gracefully already. If we just remove RecoveryInfoLock, that can happen, > but it still won't be possible for a lock to be missed out which is what > we really care about.
I see the problem with that now. Without the lock, it's possible that the XLOG_RELATION_LOCK WAL record is written before the XLOG_RUNNING_XACTS record. If the lock is not included in the snapshot, we want the lock WAL record to be after the snapshot record. So i guess we'll need the RecoveryInfoLock. But we don't need to hold it across the wait. I think it's enough to acquire it just before writing the WAL record in LockAcquire. That will ensure that the WAL record isn't written until the snapshot is completely finished. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
