Check that oldestXID and oldestMulti are consistent at pg_upgrade
Now that pg_upgrade will rewrite multixid members, starting from
oldestMulti, it's important that oldestMulti is valid. Add a sanity
check that oldestMulti is not newer than the oldest datminmxid value
in pg_database.
One case where this could happen is if the cluster was previously
upgraded to version 9.3 with a buggy pg_upgrade version that didn't
have commit a61daa14d5. This new pg_upgrade check is similar to the
defence that was added in commit 78db307bb2 to VACUUM to avoid
truncating away multixids if oldestMulti is too new. This pg_upgrade
check differs in that we don't try to soldier on with the upgrade if
the oldestMultiXID is inconsistent, but rather just abort the upgrade.
Reported-by: Noah Misch <noah@leadboat.com>
Discussion: https://www.postgresql.org/message-id/20260827231757.78.noahmisch@microsoft.com
Backpatch-through: 19
Branch
------
REL_19_STABLE
Details
-------
https://git.postgresql.org/pg/commitdiff/5cd84ed6274ecd552f2991c54710608c0ef4cdc7
Modified Files
--------------
src/backend/access/transam/multixact.c | 28 --------------
src/bin/pg_upgrade/check.c | 71 ++++++++++++++++++++++++++++++++++
src/include/access/multixact.h | 31 +++++++++++++--
3 files changed, 99 insertions(+), 31 deletions(-)
