Hot standby, running xacts, subtransactions

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.

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