Alvaro Herrera <alvherre@commandprompt.com> writes:
> As far as I can see, for the purposes of VACUUM we can remove any tuple
> that was deleted after the old transaction's Xid but before that
> transaction's Xmin (i.e. all of its live snapshots). This means we get
> to ignore Xid in GetOldestXmin and in the TransactionXmin calculations
> in GetSnapshotData. It would not surprise me, however, to find out that
> I am overlooking something and this is incorrect.
This seems entirely off-base to me. In particular, if a transaction
has an XID then its XMIN will never be greater than that, so I don't
even see how you figure the case will arise.
regards, tom lane
