The user_defined_functions
table
contains a row for each loadable function registered
automatically by a component or plugin, or manually by a
CREATE
FUNCTION
statement. For information about operations
that add or remove table rows, see
Section 7.7.1, “Installing and Uninstalling Loadable Functions”.
The name of the
user_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).
The user_defined_functions
table
has these columns:
UDF_NAME
The function name as referred to in SQL statements. The value is
NULL
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 of
int
,decimal
,real
,char
, orrow
.UDF_TYPE
The function type. The value is one of
function
(scalar) oraggregate
.UDF_LIBRARY
The name of the library file containing the executable function code. The file is located in the directory named by the
plugin_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.
The user_defined_functions
table
has these indexes:
Primary key on (
UDF_NAME
)
TRUNCATE TABLE
is not permitted
for the user_defined_functions
table.
The mysql.func
system table also lists
installed loadable functions, but only those installed using
CREATE
FUNCTION
. The
user_defined_functions
table
lists loadable functions installed using
CREATE
FUNCTION
as well as loadable functions installed
automatically by components or plugins. This difference makes
user_defined_functions
preferable
to mysql.func
for checking which loadable
functions are installed.