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Update outdated comment on WAL-logged locks with invalid XID

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We haven't generated those for a long time.

Discussion: https://www.postgresql.org/message-id/b439edfc-c5e5-43a9-802d-4cb51ec20646@iki.fi
This commit is contained in:
Heikki Linnakangas 2024-10-21 14:28:43 +03:00
parent 1a43de5e0a
commit 3c7d78427e
1 changed files with 3 additions and 7 deletions
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10
src/backend/storage/ipc/standby.c
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@ -1121,6 +1121,9 @@ StandbyReleaseAllLocks(void)
* StandbyReleaseOldLocks * StandbyReleaseOldLocks
* Release standby locks held by top-level XIDs that aren't running, * Release standby locks held by top-level XIDs that aren't running,
* as long as they're not prepared transactions. * as long as they're not prepared transactions.
*
* This is needed to prune the locks of crashed transactions, which didn't
* write an ABORT/COMMIT record.
*/ */
void void
StandbyReleaseOldLocks(TransactionId oldxid) StandbyReleaseOldLocks(TransactionId oldxid)
@ -1266,13 +1269,6 @@ standby_redo(XLogReaderState *record)
* transactions already committed, since those commits raced ahead when * transactions already committed, since those commits raced ahead when
* making WAL entries. * making WAL entries.
* *
* The loose timing also means that locks may be recorded that have a
* zero xid, since xids are removed from procs before locks are removed.
* So we must prune the lock list down to ensure we hold locks only for
* currently running xids, performed by StandbyReleaseOldLocks().
* Zero xids should no longer be possible, but we may be replaying WAL
* from a time when they were possible.
*
* For logical decoding only the running xacts information is needed; * For logical decoding only the running xacts information is needed;
* there's no need to look at the locking information, but it's logged anyway, * there's no need to look at the locking information, but it's logged anyway,
* as there's no independent knob to just enable logical decoding. For * as there's no independent knob to just enable logical decoding. For