Within psql you can use \df to list a postgres function with a given
name
> \df now
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+------+--------------------------+---------------------+--------
pg_catalog | now | timestamp with time zone | | normal
(1 row)When a function has multiple definitions across a number of types, \df
will list all versions of that function
> \df generate_series
List of functions
-[ RECORD 1 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF bigint
Argument data types | bigint, bigint
Type | normal
-[ RECORD 2 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF bigint
Argument data types | bigint, bigint, bigint
Type | normal
-[ RECORD 3 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF integer
Argument data types | integer, integer
Type | normal
-[ RECORD 4 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF integer
Argument data types | integer, integer, integer
Type | normal
-[ RECORD 5 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF timestamp with time zone
Argument data types | timestamp with time zone, timestamp with time zone, interval
Type | normal
-[ RECORD 6 ]-------+-------------------------------------------------------------------
Schema | pg_catalog
Name | generate_series
Result data type | SETOF timestamp without time zone
Argument data types | timestamp without time zone, timestamp without time zone, interval
Type | normal