One other nit re. the predicate lock table size GUCs: the out-of-memory
case in RegisterPredicateLockingXid (predicate.c:1592 in my tree) gives
the hint to increase max_predicate_locks_per_transaction. I don't think
that's correct, since that GUC isn't used to size SerializableXidHash.
In fact, that error shouldn't arise at all because if there was room in
PredXact to register the transaction, then there should be room to
register it's xid in SerializableXidHash. Except that it's possible for
something else to allocate all of our shared memory and thus prevent
SerializbleXidHash from reaching its intended max capacity.
In general, it might be worth considering making a HTAB's max_size a
hard limit, but that's a larger issue. Here, it's probably worth just
removing the hint.
Dan
--
Dan R. K. Ports MIT CSAIL http://drkp.net/