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29.12.22.12 The user_defined_functions Table

Theuser_defined_functions table contains a row for each loadable function registered automatically by a component or plugin, or manually by aCREATE FUNCTION statement. For information about operations that add or remove table rows, seeSection 7.7.1, “Installing and Uninstalling Loadable Functions”.

Note

The name of theuser_defined_functions table stems from the terminology used at its inception for the type of function now known as a loadable function (that is, user-defined function, or UDF).

Theuser_defined_functions table has these columns:

  • UDF_NAME

    The function name as referred to in SQL statements. The value isNULL if the function was registered by aCREATE FUNCTION statement and is in the process of unloading.

  • UDF_RETURN_TYPE

    The function return value type. The value is one ofint,decimal,real,char, orrow.

  • UDF_TYPE

    The function type. The value is one offunction (scalar) oraggregate.

  • UDF_LIBRARY

    The name of the library file containing the executable function code. The file is located in the directory named by theplugin_dir system variable. The value isNULL if the function was registered by a component or plugin rather than by aCREATE FUNCTION statement.

  • UDF_USAGE_COUNT

    The current function usage count. This is used to tell whether statements currently are accessing the function.

Theuser_defined_functions table has these indexes:

  • Primary key on (UDF_NAME)

TRUNCATE TABLE is not permitted for theuser_defined_functions table.

Themysql.func system table also lists installed loadable functions, but only those installed usingCREATE FUNCTION. Theuser_defined_functions table lists loadable functions installed usingCREATE FUNCTION as well as loadable functions installed automatically by components or plugins. This difference makesuser_defined_functions preferable tomysql.func for checking which loadable functions are installed.