On Wed, 2009-02-25 at 22:39 +0200, Heikki Linnakangas wrote:
> When we take the snapshot of running transactions in the master, in
> GetRunningTransactionData(), it only includes top-level xids and those
> subxids that are in the subxid caches. Overflowed subxids are not
> included. Isn't that a problem? When the standby initializes the
> recovery procs using the running xacts information, pg_subtrans doesn't
> isn't set for the overflowed xids, because that information is not
> included in the WAL record. If you're lucky, the information is there
> already, but we don't generally guarantee pg_subtrans to survive crash
> or restart.
That is exactly the reason why we don't treat an overflowed snapshot as
a valid starting point.
-- Simon Riggs www.2ndQuadrant.comPostgreSQL Training, Services and Support