On Tue, Oct 3, 2017 at 8:43 PM, Wong, Yi Wen <yiw...@amazon.com> wrote: > My interpretation of README.HOT is the check is just to ensure the chain is > continuous; in which case the condition should be: > >> if (TransactionIdIsValid(priorXmax) && >> !TransactionIdEquals(priorXmax, >> HeapTupleHeaderGetRawXmin(htup))) >> break; > > So the difference is GetRawXmin vs GetXmin, because otherwise we get the > FreezeId instead of the Xmin when the transaction happened
I was thinking along similar lines. > The interesting consequence of changing that is the prune seems to get the > entire chain altogether with Dan's repro... I've run it a couple of times and > have consistently gotten the following page > > lp | t_ctid | lp_off | lp_flags | t_infomask | t_infomask2 > ----+--------+--------+----------+------------+------------- > 1 | (0,1) | 8152 | 1 | 2818 | 3 > 2 | | 7 | 2 | | > 3 | | 0 | 0 | | > 4 | | 0 | 0 | | > 5 | | 0 | 0 | | > 6 | | 0 | 0 | | > 7 | (0,7) | 8112 | 1 | 11010 | 32771 > (7 rows) That's also what I see. This is a good thing, I think; that's how we ought to prune. -- Peter Geoghegan -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
