MySQL - different engines for different tables

Question

MySQL allows you to specify a different mechanism for the table from the server by default. What overhead does this create? If I wanted to join a table that uses InnoDB with a table that uses MyISAM, which engine uses MySQL to run queries on this temp table? For example, if I wanted to perform a task on this summary temp table that only one engine can do (for example, full-text indexing), can the MySQL optimizer use the correct engine?

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

Answer 1

There is a penalty for moving storage systems. See here for more details.