From dd3682982ba7d1af866f72cbf4bad7b876fa68d9 Mon Sep 17 00:00:00 2001
From: Onder Kalaci <onderkalaci@gmail.com>
Date: Fri, 17 Mar 2023 09:39:15 +0300
Subject: [PATCH v1] Ignore dropped columns when REPLICA IDENTITY FULL

Dropped columns are filled with NULL values on slot_store_data()
but not on table_scan_getnextslot(). With this commit, we skip
such columns while checking tuple equality.
---
 src/backend/executor/execReplication.c |  7 ++++
 src/test/subscription/t/100_bugs.pl    | 51 ++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 6289322127..b3ba1aa6c8 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -242,6 +242,13 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2)
 		Form_pg_attribute att;
 		TypeCacheEntry *typentry;
 
+		/*
+		 * Ignore dropped columns as the publisher doesn't send those
+		 */
+		att = TupleDescAttr(slot1->tts_tupleDescriptor, attrnum);
+		if (att->attisdropped)
+			continue;
+
 		/*
 		 * If one value is NULL and other is not, then they are certainly not
 		 * equal
diff --git a/src/test/subscription/t/100_bugs.pl b/src/test/subscription/t/100_bugs.pl
index cbf46a3d33..3e7071de38 100644
--- a/src/test/subscription/t/100_bugs.pl
+++ b/src/test/subscription/t/100_bugs.pl
@@ -69,6 +69,57 @@ pass('index predicates do not cause crash');
 $node_publisher->stop('fast');
 $node_subscriber->stop('fast');
 
+# The bug was that when the REPLICA IDENTITY FULL is used with dropped columns,
+# we fail to apply updates and deletes
+my $node_publisher_d_cols = PostgreSQL::Test::Cluster->new('node_publisher_d_cols');
+$node_publisher_d_cols->init(allows_streaming => 'logical');
+$node_publisher_d_cols->start;
+
+my $node_subscriber_d_cols = PostgreSQL::Test::Cluster->new('node_subscriber_d_cols');
+$node_subscriber_d_cols->init(allows_streaming => 'logical');
+$node_subscriber_d_cols->start;
+
+$node_publisher_d_cols->safe_psql(
+	'postgres', qq(
+	CREATE TABLE dropped_cols (a int, b_drop int, c int);
+	ALTER TABLE dropped_cols REPLICA IDENTITY FULL;
+	CREATE PUBLICATION pub_dropped_cols FOR TABLE dropped_cols;
+	-- some initial data
+	INSERT INTO dropped_cols VALUES (1, 1, 1);
+));
+
+$node_subscriber_d_cols->safe_psql(
+	'postgres', qq(
+	 CREATE TABLE dropped_cols (a int, b_drop int, c int);
+));
+
+my $publisher_connstr_d_cols = $node_publisher_d_cols->connstr . ' dbname=postgres';
+$node_subscriber_d_cols->safe_psql('postgres',
+	"CREATE SUBSCRIPTION sub_dropped_cols CONNECTION '$publisher_connstr_d_cols' PUBLICATION pub_dropped_cols"
+);
+$node_subscriber_d_cols->wait_for_subscription_sync;
+
+$node_publisher_d_cols->safe_psql(
+	'postgres', qq(
+		ALTER TABLE dropped_cols DROP COLUMN b_drop;
+));
+$node_subscriber_d_cols->safe_psql(
+	'postgres', qq(
+		ALTER TABLE dropped_cols DROP COLUMN b_drop;
+));
+
+$node_publisher_d_cols->safe_psql(
+	'postgres', qq(
+		UPDATE dropped_cols SET a = 100;
+));
+$node_publisher_d_cols->wait_for_catchup('sub_dropped_cols');
+
+is($node_subscriber_d_cols->safe_psql('postgres', "SELECT count(*) FROM dropped_cols WHERE a = 100"),
+	qq(1), 'replication with RI FULL and dropped columns');
+
+$node_publisher_d_cols->stop('fast');
+$node_subscriber_d_cols->stop('fast');
+
 
 # Handling of temporary and unlogged tables with FOR ALL TABLES publications
 
-- 
2.34.1