On Thu, Jun 20, 2024 at 7:42 PM Melanie Plageman <melanieplage...@gmail.com> wrote: > > If vacuum fails to remove a tuple with xmax older than > VacuumCutoffs->OldestXmin and younger than > GlobalVisState->maybe_needed, it will ERROR out when determining > whether or not to freeze the tuple with "cannot freeze committed > xmax".
One thing I don't understand is why it is okay to freeze the xmax of a dead tuple just because it is from an aborted update. heap_prepare_freeze_tuple() is called on HEAPTUPLE_RECENTLY_DEAD tuples with normal xmaxes (non-multis) so that it can freeze tuples from aborted updates. The only case in which we freeze dead tuples with a non-multi xmax is if the xmax is from before OldestXmin and is also not committed (so from an aborted update). Freezing dead tuples replaces their xmax with InvalidTransactionId -- which would make them look alive. So, it makes sense we don't do this for dead tuples in the common case. But why is it 1) okay and 2) desirable to freeze xmaxes of tuples from aborted updates? Won't it make them look alive again? - Melanie
