From 34bd7699be3b9d53cb2a56f2fa5ae1fb94f4d300 Mon Sep 17 00:00:00 2001
From: Ashwin Agrawal <aagrawal@pivotal.io>
Date: Tue, 20 Mar 2018 10:58:30 -0700
Subject: [PATCH] PANIC in debug for "local snapshot's xmin is older".

To help debug the issue, PANIC incase encounter this shouldn't happen case.
---
 src/backend/access/transam/distributedlog.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/backend/access/transam/distributedlog.c b/src/backend/access/transam/distributedlog.c
index 97946d18f0..bdd85a105f 100644
--- a/src/backend/access/transam/distributedlog.c
+++ b/src/backend/access/transam/distributedlog.c
@@ -216,7 +216,15 @@ DistributedLog_AdvanceOldestXmin(TransactionId oldestLocalXmin,
 
 	/* sanity check, this shouldn't happen... */
 	if (TransactionIdFollows(oldestXmin, oldestLocalXmin))
-		elog(ERROR, "local snapshot's xmin is older than recorded distributed oldestxmin");
+	{
+#ifdef USE_ASSERT_CHECKING
+		elog(PANIC,
+#else
+		elog(ERROR,
+#endif
+			 "local snapshot's xmin (%u) is older than recorded distributed oldestxmin (%u)",
+			 oldestLocalXmin, oldestXmin);
+	}
 
 	currPage = -1;
 	while (!TransactionIdEquals(oldestXmin, oldestLocalXmin))
-- 
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