On Mon, Apr 27, 2020 at 11:51 AM Alexander Korotkov <a.korot...@postgrespro.ru> wrote: > On Wed, Apr 22, 2020 at 7:47 PM Peter Geoghegan <p...@bowt.ie> wrote: > > On Tue, Apr 21, 2020 at 2:54 AM Alexander Korotkov > > <a.korot...@postgrespro.ru> wrote: > > > Proposed fix is attached. Spotted by Konstantin Knizhnik, > > > reproduction case and fix from me. > > > > I wonder if we should fix btree_xlog_unlink_page() instead of amcheck. > > We already know that its failure to be totally consistent with the > > primary causes problems for backwards scans -- this problem can be > > fixed at the same time: > > > > https://postgr.es/m/cantu0ohkr-evawbpzju54v8ecotqjjyyp3pq_sgobtrgxwh...@mail.gmail.com > > > > We'd probably still use your patch for the backbranches if we went this way. > > > > What do you think? > > I've skip through the thread. It seems to be quite independent issue > from this one. This issue is related to the fact that we leave some > items on deleted pages on primary, and on the same time we have no > items on deleted pages on standby. This inconsistency cause amcheck > pass normally on primary, but fail on standby. BackwardScan on > standby issue seems to be related solely on locking protocol and > btpo_prev, btpo_next pointers. It wasn't mention on that thread that > we might need hikeys on deleted pages. > > Assuming it doesn't seem we actually need any items on deleted pages, > I can propose to delete them on primary as well. That would make > contents of primary and standby more consistent. What do you think?
So, my proposal is following. Backpatch my fix upthread to 11. In master additionally make _bt_unlink_halfdead_page() remove page items on primary as well. Do you have any objections? ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
