On Tue, Apr 28, 2020 at 4:05 AM Peter Geoghegan <p...@bowt.ie> wrote: > On Mon, Apr 27, 2020 at 4:17 AM Alexander Korotkov > <a.korot...@postgrespro.ru> wrote: > > > 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? > > What I meant was that we might as well review the behavior of > _bt_unlink_halfdead_page() here, since we have to change it anyway. > But I think you're right: No matter what happens or doesn't happen to > _bt_unlink_halfdead_page(), the fact is that deleted pages may or may > not have a single remaining item (which was originally the "top > parent" item from the page at offset number P_HIKEY), now and forever. > We have to conservatively assume that it could be either state, now > and forever. That means that we definitely have to give up on the > check, per your patch. So, +1 for backpatching that back to 11.
Thank you. I've worked a bit on comments and commit message. I would appreciate you review. > (BTW, I don't think that this is a concurrency issue, except in the > sense that a test case that recreates the false positive is sensitive > to concurrency -- I imagine you agree with this.) Yes, I agree it's related to concurrency, but not exactly concurrency issue. > I like your idea of making the primary consistent with the REDO > routine on the master branch only. I wonder if that will make it > possible to change btree_mask() so that wal_consistency_checking can > check deleted pages as well. The contents of a deleted page's special > area do matter, and yet we don't currently verify that it matches (we > use mask_page_content() within btree_mask() for deleted pages, which > seems inappropriately broad). In particular, the left and right > sibling links should be consistent with the primary on a deleted page. Thank you. 2nd patch is proposed for master and makes btree page unlink remove all the items from the page being deleted. ------ Alexander Korotkov Postgres Professional: http://www.postgrespro.com The Russian Postgres Company
0001-Fix-amcheck-for-page-checks-concurrent-to-replay-of-.patch
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0002-Remove-btree-page-items-after-page-unlink.patch
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