From a3e992fb518f27cd05ecca7aa2df42787f8baebd Mon Sep 17 00:00:00 2001
From: Arseny Sher <sher-ars@yandex.ru>
Date: Mon, 8 Nov 2021 15:59:23 +0300
Subject: [PATCH] Handle keepalives while receiving WAL in recovery.

Since c310932 safekeeper sometimes sends it.

ref #843
---
 src/backend/replication/walproposer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/backend/replication/walproposer.c b/src/backend/replication/walproposer.c
index 667d18ba56e..618c8992f57 100644
--- a/src/backend/replication/walproposer.c
+++ b/src/backend/replication/walproposer.c
@@ -978,7 +978,9 @@ WalProposerRecovery(int donor, TimeLineID timeline, XLogRecPtr startpos, XLogRec
 			}
 			else
 			{
-				Assert(buf[0] == 'w');
+				Assert(buf[0] == 'w' || buf[0] == 'k');
+				if (buf[0] == 'k')
+					continue; /* keepalive */
 				memcpy(&rec_start_lsn, &buf[XLOG_HDR_START_POS],
 					   sizeof rec_start_lsn);
 				rec_start_lsn = pg_ntoh64(rec_start_lsn);