\df [ PATTERN ]

The \df [ PATTERN ] meta-command returns all function names, the function return data type, and the function argument data type. Also returns the procedure names and arguments for all procedures that are available to the user.

vmartdb=> \df
                          List of functions
  procedure_name | procedure_return_type | procedure_argument_types
-----------------+-----------------------+---------------------------
 abs             | Float                 | Float
 abs             | Integer               | Integer
 abs             | Interval              | Interval
 abs             | Interval              | Interval
 abs             | Numeric               | Numeric
 acos            | Float                 | Float
...
 width_bucket    | Integer               | Float, Float, Float, Integer
 width_bucket    | Integer               | Interval, Interval, Interval, Integer
 width_bucket    | Integer               | Interval, Interval, Interval, Integer
 width_bucket    | Integer               | Timestamp, Timestamp, Timestamp, Integer
...

The following example uses the wildcard character to search for all functions that begin with as:

vmartdb=> \df as*
                         List of functions
 procedure_name | procedure_return_type | procedure_argument_types
----------------+-----------------------+--------------------------
 ascii          | Integer               | Varchar
 asin           | Float                 | Float
(2 rows)