FEDERATED Storage Engine Resources •Transactions are not supported. • FEDERATED  performs bulk-insert handling such that multiple rows are sent to the remote table in a batch, which improves performance. Also, if the remote table is transactional, it enables the remote storage engine to perform statement rollback properly should an error occur. This capability has the following limitations: •The size of the insert cannot exceed the maximum packet size between servers. If the insert exceeds this size, it is broken into multiple packets and the rollback problem can occur. •Bulk-insert handling does not occur for  INSERT ... ON DUPLICATE KEY UPDATE . •There is no way for the  FEDERATED  engine to know if the remote table has changed. The reason for this is that this table must work like a data file that would never be written to by anything other than the database system. The integrity of the data in the local table could be breached if there was any change to the remote database. •When using a  CONNECTION  string, you cannot use an ’@’ character in the password. You can get round this limitation by using the  CREATE SERVER  statement to create a server connection. •The  insert_id  and  timestamp  options are not propagated to the data provider. •Any  DROP TABLE  statement issued against a  FEDERATED  table drops only the local table, not the remote table. •User-defined partitioning is not supported for  FEDERATED  tables. •A forum dedicated to the  FEDERATED  storage engine is available at https://forums.mysql.com/list.php? 105. 16.8.4 FEDERATED Storage Engine Resources 16.9 The EXAMPLE Storage Engine The following additional resources are available for the  FEDERATED  storage engine: The  EXAMPLE  storage engine is a stub engine that does nothing. Its purpose is to serve as an example in the MySQL source code that illustrates how to begin writing new storage engines. As such, it is primarily of interest to developers. To enable the  EXAMPLE  storage engine if you build MySQL from source, invoke  CMake  with the  - DWITH_EXAMPLE_STORAGE_ENGINE  option. To examine the source for the  EXAMPLE  engine, look in the  storage/example  directory of a MySQL source distribution. When you create an  EXAMPLE  table, no files are created. No data can be stored into the table. Retrievals return an empty result. mysql>  CREATE TABLE test (i INT) ENGINE = EXAMPLE; Query OK, 0 rows affected (0.78 sec) mysql>  INSERT INTO test VALUES(1),(2),(3); ERROR 1031 (HY000): Table storage engine for ’test’ doesn’t » have this option mysql>  SELECT * FROM test; Empty set (0.31 sec) 3431