GiST: Invalidate killed items consistently. GiST neglected to invalidate its killedItems[] array on a rescan. As a result, it was just about possible for the wrong tuples from the wrong index page to be LP_DEAD-marked on a rescan. The scan mistakenly believed that the previous rescan's killedItems[] were for this rescan's curBlkno, causing index corruption.
To fix, bring GiST in line with nbtree and hash: call gistkillitems from both gistrescan and gistendscan (the existing gistgettuple caller still handles the common case where we need to LP_DEAD-mark before moving on to the next page). That way the scan's pending killedItems[] are passed to gistkillitems while they still describe items from curBlkno. When gistkillitems runs, it'll invalidate the array in passing (and won't needlessly miss out on an opportunity to LP_DEAD-mark eligible index tuples). Back branches just get minimal hardening: we invalidate killedItems[] at the places where the master branch gets new calls to gistkillitems (and we invalidate curBlkno and curPageLSN on a rescan). The test that proved corruption on master didn't result in corruption on any stable branch, though only because, without commit 9c9ddf109, we'd clobber curPageLSN without also updating curBlkno -- which accidentally prevented it. Relying on gistkillitems to not LP_DEAD-mark by passing it a curBlkno whose curPageLSN was taken from an entirely different page seems like a very bad idea, which is why this issue is being treated as a bug affecting all stable branches. Author: Peter Geoghegan <[email protected]> Reviewed-By: Andrey Borodin <[email protected]> Discussion: https://postgr.es/m/CAH2-WzmwEThnQf17Ju+t0N9_KJLsEQSXzYrFnaS2=s4kngg...@mail.gmail.com Backpatch-through: 14 Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/cb217c4f174f487009bcba3812bbf23b8d8eba4c Modified Files -------------- src/backend/access/gist/gistget.c | 44 ++++++++++++++++++++++---------------- src/backend/access/gist/gistscan.c | 10 +++++++++ src/include/access/gist_private.h | 1 + 3 files changed, 36 insertions(+), 19 deletions(-)
