Ignore generated columns during apply of update/delete.

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

Author: Onder Kalaci
Reviewed-by: Shi yu, Amit Kapila
Backpatch-through: 12
Discussion: https://postgr.es/m/CACawEhVQC9WoofunvXg12aXtbqKnEgWxoRx3+v8q32AWYsdpGg@mail.gmail.com

Author: Amit Kapila

src/backend/executor/execReplication.c

@@ -292,9 +292,10 @@ tuples_equal(TupleTableSlot *slot1, TupleTableSlot *slot2,
 		att = TupleDescAttr(slot1->tts_tupleDescriptor, attrnum);
 
 		/*
-		 * Ignore dropped columns as the publisher doesn't send those
+		 * Ignore dropped and generated columns as the publisher doesn't send
+		 * those
 		 */
-		if (att->attisdropped)
+		if (att->attisdropped || att->attgenerated)
 			continue;
 
 		/*

src/test/subscription/t/100_bugs.pl

@@ -377,8 +377,8 @@
 $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
+# The bug was that when the REPLICA IDENTITY FULL is used with dropped or
+# generated columns, we fail to apply updates and deletes
 $node_publisher->rotate_logfile();
 $node_publisher->start();
 
@@ -389,14 +389,18 @@
 	'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;
+	CREATE TABLE generated_cols (a int, b_gen int GENERATED ALWAYS AS (5 * a) STORED, c int);
+	ALTER TABLE generated_cols REPLICA IDENTITY FULL;
+	CREATE PUBLICATION pub_dropped_cols FOR TABLE dropped_cols, generated_cols;
 	-- some initial data
 	INSERT INTO dropped_cols VALUES (1, 1, 1);
+	INSERT INTO generated_cols (a, c) VALUES (1, 1);
 ));
 
 $node_subscriber->safe_psql(
 	'postgres', qq(
 	 CREATE TABLE dropped_cols (a int, b_drop int, c int);
+	 CREATE TABLE generated_cols (a int, b_gen int GENERATED ALWAYS AS (5 * a) STORED, c int);
 ));
 
 $publisher_connstr = $node_publisher->connstr . ' dbname=postgres';
@@ -417,6 +421,7 @@
 $node_publisher->safe_psql(
 	'postgres', qq(
 		UPDATE dropped_cols SET a = 100;
+		UPDATE generated_cols SET a = 100;
 ));
 $node_publisher->wait_for_catchup('sub_dropped_cols');
 
@@ -425,6 +430,11 @@
 	qq(1),
 	'replication with RI FULL and dropped columns');
 
+is( $node_subscriber->safe_psql(
+		'postgres', "SELECT count(*) FROM generated_cols WHERE a = 100"),
+	qq(1),
+	'replication with RI FULL and generated columns');
+
 $node_publisher->stop('fast');
 $node_subscriber->stop('fast');