Avoid using tuple from syscache for update of pg_database.datfrozenxid pg_database.datfrozenxid gets updated using an in-place update at the end of vacuum or autovacuum. Since 96cdeae, as pg_database has a toast relation, it is possible for a pg_database tuple to have toast values if there is a large set of ACLs in place. In such a case, the in-place update would fail because of the flattening of the toast values done for the catcache entry fetched. Instead of using a copy from the catcache, this changes the logic to fetch the copy of the tuple by directly scanning pg_database.
Note that before 96cdeae, attempting to insert such a tuple to pg_database would cause a "row is too big" error, so the end-of-vacuum problem was not reachable. This issue has been originally fixed in 947789f on v14~, and there have been reports about this problem on v12 and v13, causing failures at the end of VACUUM. This completes the fix on all the stable branches where pg_database can use a toast table, down to 12. Author: Ashwin Agrawal, Junfeng Yang Discussion: https://postgr.es/m/dm5pr0501mb38800d9e4605bca72dd35557cc...@dm5pr0501mb3880.namprd05.prod.outlook.com Discussion: https://postgr.es/m/y70xnvbuwqsr2...@paquier.xyz Backpatch-through: 12 Branch ------ REL_13_STABLE Details ------- https://git.postgresql.org/pg/commitdiff/72b6098be47e19eff50a052676908e0fde25e7ee Modified Files -------------- src/backend/access/heap/heapam.c | 4 ++++ src/backend/commands/vacuum.c | 21 +++++++++++++++++++-- 2 files changed, 23 insertions(+), 2 deletions(-)