Fix GIN VACUUM posting tree root split bug. ginVacuumPostingTreeLeaves swaps a shared buffer lock for an exclusive one when it encounters a leaf page. It neglected to re-verify whether a page that was initially a leaf root page became an internal page due to a concurrent root page split (during the window when no lock was held). It was therefore possible for GIN VACUUM to spuriously treat an internal page as a leaf page, leading to data corruption. VACUUM could miss dead TIDs that it was required to remove, leaving behind dangling references in the index.
To fix, re-verify that a leaf page is still a leaf page after an exclusive lock is acquired. If it isn't, drop our exclusive lock and acquire a shared lock so that the non-leaf root page gets processed in the usual way. Oversight in commit fd83c83d, which fixed a deadlock bug in GIN posting tree vacuuming. Author: Peter Geoghegan <[email protected]> Reviewed-by: Andrey Borodin <[email protected]> Discussion: https://postgr.es/m/CAH2-Wz=RBpJTQgvOxr6C=j04dexmfst1e3f-r+crtq56heo...@mail.gmail.com Backpatch-through: 14 Branch ------ REL_16_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/dd1634ddbdbb72deb43482c9b6435c7a9c38da9a Modified Files -------------- src/backend/access/gin/ginvacuum.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
