"Eric B. Ridge" <ebr@xxxxxxxx> writes: > Outside of "VACUUM FREEZE", is there any way the "xmin" column in a > relation can change, assuming of course the tuple is never updated > again? If the tuple lives long enough, VACUUM will change it to FrozenTransactionId eventually, even without the FREEZE option. > I'm considering using this as a way to identify all tuples > modified in the same transaction (in an effort to group them > together), and am wondering if there's any way tuples from different > transactions could end up with the same xmin value. This seems OK as long as the transaction was fairly recent. Note that you will need a fairly restrictive definition of "same transaction" (no subtransactions). regards, tom lane
