Creative uses for the blackhole engine

According to the documentation:

http://dev.mysql.com/doc/refman/5.0/en/blackhole-storage-engine.html

the blackhole storage engine can be used for things like diagnostics and offloading the binary log to a different machine, without having to store the database on that machine.

Wha开发者_JS百科t other creative uses for this engine can you come up with?

Found one a using a trigger:

If you have a complicated series of inserts or updates that needs to happen in a transaction, you can do these in application code, or

You can create one 'big' blackhole table with enough rows to hold all the values.

And create a trigger like:

DELIMITER $$

CREATE TRIGGER ai_bh_table_each AFTER INSERT ON bh_table FOR EACH ROW
BEGIN
  DECLARE lastid1 integer;

  INSERT INTO table1 VALUES (null, new.field1, new.field2);
  SELECT LAST_INSERT_ID() INTO lastid1;
  INSERT INTO table2 VALUES (null, new.field3, lastid1);
  ....  
END$$

DELIMITER ;

If you include error checking code you can even simulate transactions on engines that don't support it, like MyISAM.

Seems to be a great "mock" database for program-testing purposes.

I often use Python's internal SQLite database for such things, but having a MySQL-specific mock database would be nice; thanks for sharing.

(A unit-test could, as a last step, drop the test tables; etc. But the "blackhole" engine would obviate that step.)