Isn't the snapshotOldestActiveXid filter in
RecordKnownAssignedTransactionIds completely wrong/useless/bogus?
AFAICS, snapshotOldestActiveXid is only set once at the start of
recovery. This means it will soon be too old to provide any useful
filtering. But what's far worse is that the XID space will eventually
wrap around, and that test will start filtering *everything*.
I think we should just lose that test, as well as the variable.
regards, tom lane