From: Simon Riggs <simon@2ndQuadrant.com>
Date: Fri, 26 Jun 2015 23:48:06 +0000 (+0100)
Subject: Avoid hot standby cancels from VAC FREEZE
X-Git-Tag: REL9_1_19~100
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9e23d05b256adb0964f13464f9be5ae6e856cd19;p=postgresql

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 6645732f74..634c0313c9 100644
--- 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))