default_tmp_storage_engine variable was introduced in 5.6.3, allowing the configuration of the default engine for temporary tables. This seems to be in the direction, as I commented before, of making MyISAM an optional engine. In 5.7, a separate tablespace is being
Regarding MySQL 5.6 temporary tables format
![Regarding MySQL 5.6 temporary tables format A temporary table](https://jynus.com/dbahire/wp-content/uploads/2015/02/temporary-table.png)