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 6645732f74c2f51974d3e2d12e2f0dc120048e32..634c0313c944e3fe472d6aca448ffaccd63e28e0 100644 (file)
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -4307,7 +4307,13 @@ 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))