5.6.2 Obtaining Information About Loadable Functions

The mysql.func system table shows which loadable functions have been registered using CREATE FUNCTION:

SELECT * FROM mysql.func;

The func table has these columns:

name

The function name as referred to in SQL statements.
ret

The function return value type. Permitted values are 0 (STRING), 1 (REAL), 2 (INTEGER), 3 (ROW), or 4 (DECIMAL).
dl

The name of the function library file containing the executable function code. The file is located in the directory named by the plugin_dir system variable.
type

The function type, either function (scalar) or aggregate.