Fix race condition in committing a serializable transaction
The finished transaction list can contain XIDs that are older than the
serializable global xmin. It's a short-lived state;
ClearOldPredicateLocks() removes any such transactions from the list,
and it's called whenever the global xmin advances. But if another
backend calls SummarizeOldestCommittedSxact() in that window, it will
call SerialAdd() on an XID that's older than the global xmin, or if
there are no more transactions running, when global xmin is
invalid. That trips the assertion in SerialAdd().
Fixes bug #18658 reported by Andrew Bille. Thanks to Alexander Lakhin
for analysis. Backpatch to all versions.
Discussion: https://www.postgresql.org/message-id/18658-7dab125ec688c70b%40postgresql.org
Branch
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REL_14_STABLE
Details
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https://git.postgresql.org/pg/commitdiff/520ec2474b392805ca4d7f29205e245ac70ea0e1
Modified Files
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src/backend/storage/lmgr/predicate.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)