On Thu, Jun 16, 2011 at 04:53:41PM +0100, Simon Riggs wrote: > On Thu, Jun 16, 2011 at 3:47 PM, Noah Misch <n...@leadboat.com> wrote: > > Thanks. ?We still hit a conflict when btpo.xact == RecentGlobalXmin and the > > standby has a transaction older than any master transaction. ?This happens > > because the tests at nbtpage.c:704 and procarray.c:1843 both pass when the > > xid > > exactly is that of the oldest standby transaction (line numbers as of git > > cb94db91b). ?I only know this because the test script from my last message > > hits > > this case; it might never get hit in real usage. ?Still, seems like a hole > > not > > worth leaving. ?I think the most-correct fix is to TransactionIdRetreat the > > btpo.xact before using it as xl_btree_reuse_page.lastestRemovedXid. > > ?btpo.xact > > is the first known-safe xid, but latestRemovedXid is the last known-unsafe > > xmin. > > I think you are pointing out another bug, rather than a problem in my > last commit. > > The bug was caused by assuming that the xid is a "latestRemovedXid", > as is the case in the rest of Hot Standby, which masks the off-by-one > error through poor use of terms.
Exactly. > I agree with your suggested fix. (Note that TransactionIdRetreat mutates its argument and returns nothing.) Thanks, nm -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
