Merge pilot.blaudden:/home/msvensson/mysql/bug25262/my50-bug25262

into  pilot.blaudden:/home/msvensson/mysql/mysql-5.0-maint

mysql-test/r/alter_table.result

@@ -860,3 +860,27 @@ ALTER TABLE t1 ADD d INT;
 ALTER TABLE t1 ADD KEY (d(20));
 ERROR HY000: Incorrect sub part key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique sub keys
 DROP TABLE t1;
+create table t1(id int(8) primary key auto_increment) engine=heap;
+insert into t1 values (null);
+insert into t1 values (null);
+select * from t1;
+id
+1
+2
+alter table t1 auto_increment = 50;
+alter table t1 engine = myisam;
+insert into t1 values (null);
+select * from t1;
+id
+1
+2
+50
+alter table t1 engine = heap;
+insert into t1 values (null);
+select * from t1;
+id
+1
+2
+50
+51
+drop table t1;

mysql-test/t/alter_table.test

@@ -636,3 +636,29 @@ ALTER TABLE t1 ADD d INT;
 ALTER TABLE t1 ADD KEY (d(20));
 
 DROP TABLE t1;
+# Bug#25262 Auto Increment lost when changing Engine type
+#
+
+create table t1(id int(8) primary key auto_increment) engine=heap;
+
+insert into t1 values (null);
+insert into t1 values (null);
+
+select * from t1;
+
+# Set auto increment to 50
+alter table t1 auto_increment = 50;
+
+# Alter to myisam
+alter table t1 engine = myisam;
+
+# This insert should get id 50
+insert into t1 values (null);
+select * from t1;
+
+# Alter to heap again
+alter table t1 engine = heap;
+insert into t1 values (null);
+select * from t1;
+
+drop table t1;

sql/sql_table.cc

@@ -3316,6 +3316,12 @@ bool mysql_alter_table(THD *thd,char *new_db, char *new_name,
     create_info->avg_row_length= table->s->avg_row_length;
   if (!(used_fields & HA_CREATE_USED_DEFAULT_CHARSET))
     create_info->default_table_charset= table->s->table_charset;
+  if (!(used_fields & HA_CREATE_USED_AUTO) && table->found_next_number_field)
+  {
+    /* Table has an autoincrement, copy value to new table */
+    table->file->info(HA_STATUS_AUTO);
+    create_info->auto_increment_value= table->file->auto_increment_value;
+  }
 
   restore_record(table, s->default_values);     // Empty record for DEFAULT
   List_iterator<Alter_drop> drop_it(alter_info->drop_list);