SQL: disable engine change [fixes #358]

mysql-test/suite/versioning/r/alter.result

@@ -22,6 +22,8 @@ t	CREATE TABLE `t` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1 WITH SYSTEM VERSIONING
 alter table t add column y int;
 ERROR HY000: Not allowed for versioned `test.t`. Change `versioning_alter_history` to proceed with ALTER.
+alter table t engine innodb;
+ERROR HY000: Not allowed for versioned `test.t`. Change to/from native versioning engine is prohibited.
 alter table t drop system versioning;
 show create table t;
 Table	Create Table

mysql-test/suite/versioning/t/alter.test

@@ -12,6 +12,8 @@ show create table t;
 
 --error ER_VERS_ALTER_NOT_ALLOWED
 alter table t add column y int;
+--error ER_VERS_ALTER_ENGINE_PROHIBITED
+alter table t engine innodb;
 
 alter table t drop system versioning;
 show create table t;

sql/share/errmsg-utf8.txt

@@ -7848,6 +7848,9 @@ WARN_VERS_PART_NON_HISTORICAL
 ER_VERS_ALTER_NOT_ALLOWED
         eng "Not allowed for versioned `%s.%s`. Change `versioning_alter_history` to proceed with ALTER."
 
+ER_VERS_ALTER_ENGINE_PROHIBITED
+        eng "Not allowed for versioned `%s.%s`. Change to/from native versioning engine is prohibited."
+
 ER_VERS_RANGE_PROHIBITED
         eng "SYSTEM_TIME range selector is prohibited"
 

sql/sql_table.cc

@@ -8842,11 +8842,21 @@ bool mysql_alter_table(THD *thd, const char *new_db, const char *new_name,
   bool error= open_tables(thd, &table_list, &tables_opened, 0,
                           &alter_prelocking_strategy);
   thd->open_options&= ~HA_OPEN_FOR_ALTER;
-  bool versioned= table_list->table && table_list->table->versioned();
+
+  TABLE *table= table_list->table;
+  bool versioned= table && table->versioned();
   bool vers_survival_mod= false;
 
   if (versioned)
   {
+    if (create_info->db_type &&
+      table->s->db_type() != create_info->db_type && (
+      table->file->native_versioned() ||
+      create_info->db_type->flags & HTON_NATIVE_SYS_VERSIONING))
+    {
+      my_error(ER_VERS_ALTER_ENGINE_PROHIBITED, MYF(0), table_list->db, table_list->table_name);
+      DBUG_RETURN(true);
+    }
     bool vers_data_mod= alter_info->data_modifying();
     if (thd->variables.vers_alter_history == VERS_ALTER_HISTORY_SURVIVE)
     {
@@ -8895,7 +8905,6 @@ bool mysql_alter_table(THD *thd, const char *new_db, const char *new_name,
   if (error)
     DBUG_RETURN(true);
 
-  TABLE *table= table_list->table;
   table->use_all_columns();
   MDL_ticket *mdl_ticket= table->mdl_ticket;