Merge pilot.blaudden:/home/msvensson/mysql/bug25262/my51-bug25262

into  pilot.blaudden:/home/msvensson/mysql/mysql-5.1-maint

mysql-test/r/alter_table.result

@@ -822,6 +822,30 @@ desc t1;
 Field	Type	Null	Key	Default	Extra
 mycol	int(10)	NO		0	
 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;
 create table t1 (v varchar(32));
 insert into t1 values ('def'),('abc'),('hij'),('3r4f');
 select * from t1;

mysql-test/t/alter_table.test

@@ -605,6 +605,34 @@ desc t1;
 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;
 # Some additional tests for new, faster alter table.  Note that most of the
 # whole alter table code is being tested all around the test suite already.
 #

sql/sql_table.cc

@@ -5700,6 +5700,12 @@ 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->stats.auto_increment_value;
+  }
   if (!(used_fields & HA_CREATE_USED_KEY_BLOCK_SIZE))
     create_info->key_block_size= table->s->key_block_size;