MySQL - Different Engines for Different Tables

Question

MySQL allows you to specify a different engine for a table from the server default engine. What kind of overhead does that create though? If I wanted to join a table that uses InnoDB with a table that uses MyISAM, which engine does MySQL use to run queries on that resulting temp table? For example, if I wanted to perform a task on that resulting temp table that only one engine can do (such as full text indexing), will the MySQL optimizer know to apply the right engine?

Is there any other reason not to specify particular engines for particular tables, even if they might differ from the server default?

Answer 1

There is a penalty for mixing storage engines. Take a look here for details.