Fix GIN multiple-VACUUM-scans pending list bug. ginbulkdelete performs pending list cleanup before it searches the entry tree (and any posting trees) for dead TIDs. This is necessary to avoid leaving behind dangling TID references that index vacuuming is required to remove; nothing prevents recently inserted pending list tuples from containing TIDs that VACUUM already considers dead.
However, ginbulkdelete neglected to perform pending list cleanup on VACUUM's second or subsequent call. It was therefore possible for a VACUUM that requires multiple rounds of index vacuuming to leave behind dangling references. To fix, teach ginbulkdelete to perform pending list cleanup during every call. In passing, tweak some related comments in the pending list cleanup path to make it clear why it's safe for VACUUM to not _fully_ empty an index's pending list. This was arguably an oversight in commit e2c79e14, which fixed a similar issue where pending list cleanup by VACUUM could end early, but missed this closely related problem. Author: Peter Geoghegan <[email protected]> Reviewed-by: Andrey Borodin <[email protected]> Discussion: https://postgr.es/m/cah2-wzmsa-rpa2ko8a5lagonmbpimj--71xkibqwgjk3fq8...@mail.gmail.com Backpatch-through: 14 Branch ------ REL_18_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/b0a36462bf28ad233f016f4b8ad3ce021ff9b76b Modified Files -------------- src/backend/access/gin/ginfast.c | 15 +++++++++------ src/backend/access/gin/ginvacuum.c | 18 ++++++++++++------ src/include/access/gin_private.h | 2 +- 3 files changed, 22 insertions(+), 13 deletions(-)
