Avoid hot standby cancels from VAC FREEZE

VACUUM FREEZE generated false cancelations of standby queries on an
otherwise idle master. Caused by an off-by-one error on cutoff_xid
which goes back to original commit.

Backpatch to all versions 9.0+

Analysis and report by Marco Nenciarini

Bug fix by Simon Riggs

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 2a494f59f4cf44a1c4a6751645d7920733d05ce3..44ef948f5049a66e1f6e626f0213d7eef66f9ea0 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -4725,7 +4725,13 @@ heap_xlog_freeze(XLogRecPtr lsn, XLogRecord *record)
     * consider the frozen xids as running.
     */
    if (InHotStandby)
-       ResolveRecoveryConflictWithSnapshot(cutoff_xid, xlrec->node);
+   {
+       TransactionId latestRemovedXid = cutoff_xid;
+
+       TransactionIdRetreat(latestRemovedXid);
+
+       ResolveRecoveryConflictWithSnapshot(latestRemovedXid, rnode);
+   }
 
    /* If we have a full-page image, restore it and we're done */
    if (record->xl_info & XLR_BKP_BLOCK(0))