From: Kyotaro Horiguchi <horikyoga.ntt@gmail.com>
Date: Thu, 28 May 2020 15:55:30 +0900
Subject: [PATCH v1] Fix crash when starting physical replication on logical
 connection

It is an illegal operation to try starting physical replication on a
logical replication session.  We should properly warn the client
instead of crashing.
---
 src/backend/replication/walsender.c         |  5 +++++
 src/test/recovery/t/001_stream_rep.pl       | 14 +++++++++++---
 src/test/recovery/t/006_logical_decoding.pl | 10 +++++++++-
 3 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 86847cbb54..7b79c75311 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -589,6 +589,11 @@ StartReplication(StartReplicationCmd *cmd)
 	StringInfoData buf;
 	XLogRecPtr	FlushPtr;
 
+	if (am_db_walsender)
+		ereport(ERROR,
+				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
+				 errmsg("cannot initiate physical replication on a logical replication connection")));
+
 	if (ThisTimeLineID == 0)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
diff --git a/src/test/recovery/t/001_stream_rep.pl b/src/test/recovery/t/001_stream_rep.pl
index 0c316c1808..0b69b7d8d1 100644
--- a/src/test/recovery/t/001_stream_rep.pl
+++ b/src/test/recovery/t/001_stream_rep.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 35;
+use Test::More tests => 36;
 
 # Initialize master node
 my $node_master = get_new_node('master');
@@ -18,6 +18,14 @@ my $backup_name = 'my_backup';
 # Take backup
 $node_master->backup($backup_name);
 
+# Check if logical-rep session properly refuses to start physical-rep
+my ($ret, $stdout, $stderr) =
+  $node_master->psql('template1',
+					 qq[START_REPLICATION PHYSICAL 0/1],
+					 replication=>'database');
+ok($stderr =~ /ERROR:  cannot initiate physical replication on a logical replication connection/,
+   "check if physical replication is rejected on logical-rep session");
+
 # Create streaming standby linking to master
 my $node_standby_1 = get_new_node('standby_1');
 $node_standby_1->init_from_backup($node_master, $backup_name,
@@ -94,7 +102,7 @@ sub test_target_session_attrs
 
 	# The client used for the connection does not matter, only the backend
 	# point does.
-	my ($ret, $stdout, $stderr) =
+	($ret, $stdout, $stderr) =
 	  $node1->psql('postgres', 'SHOW port;',
 		extra_params => [ '-d', $connstr ]);
 	is( $status == $ret && $stdout eq $target_node->port,
@@ -136,7 +144,7 @@ my $connstr_rep    = "$connstr_common replication=1";
 my $connstr_db     = "$connstr_common replication=database dbname=postgres";
 
 # Test SHOW ALL
-my ($ret, $stdout, $stderr) = $node_master->psql(
+($ret, $stdout, $stderr) = $node_master->psql(
 	'postgres', 'SHOW ALL;',
 	on_error_die => 1,
 	extra_params => [ '-d', $connstr_rep ]);
diff --git a/src/test/recovery/t/006_logical_decoding.pl b/src/test/recovery/t/006_logical_decoding.pl
index ee05535b1c..eefde8c3f1 100644
--- a/src/test/recovery/t/006_logical_decoding.pl
+++ b/src/test/recovery/t/006_logical_decoding.pl
@@ -7,7 +7,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 13;
+use Test::More tests => 14;
 use Config;
 
 # Initialize master node
@@ -36,6 +36,14 @@ ok( $stderr =~
 	  m/replication slot "test_slot" was not created in this database/,
 	"Logical decoding correctly fails to start");
 
+# Check if physical-rep session properly refuses to start logical-decoding
+($result, $stdout, $stderr) =
+  $node_master->psql('template1',
+					 qq[START_REPLICATION SLOT s1 LOGICAL 0/1],
+					 replication=>'true');
+ok($stderr =~ /ERROR:  logical decoding requires a database connection/,
+   "check if logical decoding is refused on physical-rep connection");
+
 $node_master->safe_psql('postgres',
 	qq[INSERT INTO decoding_test(x,y) SELECT s, s::text FROM generate_series(1,10) s;]
 );
-- 
2.18.2


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