MDEV-38623 ALTER TABLE ... ENGINE = MERGE is binlogged w/o ddl tag

mysql-test/suite/binlog/r/binlog_parallel_replication_ddl.result

@@ -1,8 +1,13 @@
+CREATE TABLE t1 (i1 int, i2 int, pk int);
+CREATE TABLE t2 (i1 int, i2 int, pk int);
+CREATE TABLE t3 LIKE t1;
 RESET MASTER;
+ALTER TABLE t3 ENGINE = MERGE UNION (t1,t2);
 CREATE OR REPLACE SEQUENCE s1;
 DROP SEQUENCE s1;
 FLUSH LOGS;
-FOUND 2 /GTID [0-9]+-[0-9]+-[0-9]+/ in mysqlbinlog.sql
+DROP TABLE t3,t2,t1;
+FOUND 3 /GTID [0-9]+-[0-9]+-[0-9]+/ in mysqlbinlog.sql
 The same as above number of samples must be found:
-FOUND 2 /GTID [0-9]+-[0-9]+-[0-9]+ ddl/ in mysqlbinlog.sql
+FOUND 3 /GTID [0-9]+-[0-9]+-[0-9]+ ddl/ in mysqlbinlog.sql
 End of the tests

mysql-test/suite/binlog/t/binlog_parallel_replication_ddl.test

@@ -4,7 +4,14 @@
 --source include/have_log_bin.inc
 --source include/have_binlog_format_mixed.inc
 
+CREATE TABLE t1 (i1 int, i2 int, pk int);
+CREATE TABLE t2 (i1 int, i2 int, pk int);
+CREATE TABLE t3 LIKE t1;
+
 RESET MASTER;
+# MDEV-38623 ALTER TABLE ... ENGINE = MERGE is binlogged w/o ddl tag.
+# Prove the DDL tag is in place.
+ALTER TABLE t3 ENGINE = MERGE UNION (t1,t2);
 
 # MDEV-27365 CREATE-or-REPLACE SEQUENCE bilogged without DDL flag
 # Prove it is logged with the DDL flag.
@@ -14,6 +21,9 @@ CREATE OR REPLACE SEQUENCE s1;
 DROP SEQUENCE s1;
 FLUSH LOGS;
 
+# cleanup
+DROP TABLE t3,t2,t1;
+
 --let $MYSQLD_DATADIR= `select @@datadir`
 --exec $MYSQL_BINLOG --base64-output=decode-rows $MYSQLD_DATADIR/master-bin.000001 > $MYSQLTEST_VARDIR/tmp/mysqlbinlog.sql
 

sql/misc_utils.h

@@ -0,0 +1,31 @@
+/* Copyright (c) 2026, MariaDB Corporation
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; version 2 of the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
+#ifndef MISC_UTILS_INCLUDED
+#define MISC_UTILS_INCLUDED
+
+template <typename T>
+class StateGuard {
+public:
+    explicit StateGuard(T& var) : ref(var), value(var) {}
+    ~StateGuard() { ref = value; }
+
+    StateGuard(const StateGuard&) = delete;
+    StateGuard& operator=(const StateGuard&) = delete;
+
+private:
+    T& ref;
+    T value;
+};
+#endif /* MISC_UTILS_INCLUDED */

sql/sql_table.cc

@@ -92,6 +92,7 @@ class Enable_wsrep_ctas_guard
 #ifdef _WIN32
 #include <io.h>
 #endif
+#include "misc_utils.h"
 
 const LEX_CSTRING primary_key_name= { STRING_WITH_LEN("PRIMARY") };
 static const LEX_CSTRING generated_by_server=
@@ -11022,6 +11023,7 @@ do_continue:;
     THD_STAGE_INFO(thd, stage_manage_keys);
     alter_table_manage_keys(table, table->file->indexes_are_disabled(),
                             alter_info->keys_onoff);
+    StateGuard<unsigned int> g(thd->transaction->stmt.m_unsafe_rollback_flags);
     if (trans_commit_stmt(thd) || trans_commit_implicit(thd))
       goto err_new_table_cleanup;
   }