Re: [HACKERS] [COMMITTERS] pgsql: Fix freezing of a dead HOT-updated tuple

On Tue, Oct 3, 2017 at 6:09 PM, Wood, Dan <hexpert@amazon.com> wrote:
> I’ve just started looking at this again after a few weeks break.

>                 if (TransactionIdIsValid(priorXmax) &&
>                         !TransactionIdEquals(priorXmax, HeapTupleHeaderGetXmin(htup)))
>                         break;

> We need to understand why these TXID equal checks exist.  Can we differentiate the cases they are protecting against
withthe two exceptions I’ve found? 

I haven't read your remarks here in full, since I'm about to stop
working for the day, but I will point out that
src/backend/access/heap/README.HOT says a fair amount about this,
under "Abort Cases".


--
Peter Geoghegan


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