From 4cdaea7a211938a2471a8481f5efb61e7a88ad36 Mon Sep 17 00:00:00 2001
From: Amit Kapila <akapila@postgresql.org>
Date: Tue, 21 Mar 2023 08:39:00 +0530
Subject: [PATCH] Ignore dropped columns during apply of update/delete.

We fail to apply updates and deletes when the REPLICA IDENTITY FULL is
used for the table having dropped columns. We didn't use to ignore dropped
columns while doing tuple comparison among the tuples from the publisher
and subscriber during apply of updates and deletes.

Author: Onder Kalaci, Shi yu
Reviewed-by: Amit Kapila
Discussion: https://postgr.es/m/CACawEhVQC9WoofunvXg12aXtbqKnEgWxoRx3+v8q32AWYsdpGg@mail.gmail.com
---
 src/backend/executor/execReplication.c | 10 ++++-
 src/test/subscription/t/100_bugs.pl    | 57 +++++++++++++++++++++++++-
 2 files changed, 64 insertions(+), 3 deletions(-)

diff --git a/src/backend/executor/execReplication.c b/src/backend/executor/execReplication.c
index 108162bb35..f54759425b 100644
--- a/src/backend/executor/execReplication.c
+++ b/src/backend/executor/execReplication.c
@@ -236,6 +236,14 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 		Form_pg_attribute att;
 		TypeCacheEntry *typentry;
 
+		att = TupleDescAttr(desc, attrnum);
+
+		/*
+		 * Ignore dropped columns as the publisher doesn't send those
+		 */
+		if (att->attisdropped)
+			continue;
+
 		/*
 		 * If one value is NULL and other is not, then they are certainly not
 		 * equal
@@ -249,8 +257,6 @@ tuple_equals_slot(TupleDesc desc, HeapTuple tup, TupleTableSlot *slot)
 		if (isnull[attrnum])
 			continue;
 
-		att = TupleDescAttr(desc, attrnum);
-
 		typentry = lookup_type_cache(att->atttypid, TYPECACHE_EQ_OPR_FINFO);
 		if (!OidIsValid(typentry->eq_opr_finfo.fn_oid))
 			ereport(ERROR,
diff --git a/src/test/subscription/t/100_bugs.pl b/src/test/subscription/t/100_bugs.pl
index 08e5f0bcb0..564e099e40 100644
--- a/src/test/subscription/t/100_bugs.pl
+++ b/src/test/subscription/t/100_bugs.pl
@@ -3,7 +3,7 @@ use strict;
 use warnings;
 use PostgresNode;
 use TestLib;
-use Test::More tests => 5;
+use Test::More tests => 6;
 
 # Bug #15114
 
@@ -177,3 +177,58 @@ is( $node_subscriber->safe_psql(
 
 $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 $node_publisher_d_cols = get_new_node('node_publisher_d_cols');
+$node_publisher_d_cols->init(allows_streaming => 'logical');
+$node_publisher_d_cols->start;
+
+my $node_subscriber_d_cols = get_new_node('node_subscriber_d_cols');
+$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 '$publisher_connstr_d_cols application_name=sub_dropped_cols' PUBLICATION pub_dropped_cols"
+);
+$node_subscriber_d_cols->wait_for_subscription_sync($node_publisher_d_cols,
+	'sub_dropped_cols');
+
+$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');