MySQL 8 Administrator???s Guide

Defining filename extensions

Storage engines must provide a list of extensions used by the storage engine associated to a given table, its data, and indexes to the MySQL server.

Extensions should be given in the form of a null-terminated string array and the same is returned when the [custom-engine.html#custom-engine-api-reference-bas_ext bas_ext()] method is called, as shown in the following block:

const char **ha_tina::bas_ext() const{  return ha_tina_exts;}

By providing extension information, you can also skip implementing DROP TABLE functionality, as the MySQL server will implement the same by closing the table and deleting all files with the extensions specified.