List of functions
 Schema |            Name            | Result data type |                         Argument data types                         |   Type   
--------+----------------------------+------------------+---------------------------------------------------------------------+----------
 public | _group_concat              | text             | text, text                                                          | FUNCTION 
 public | film_in_stock              | integer          | p_film_id integer, p_store_id integer, OUT p_film_count integer     | FUNCTION 
 public | film_not_in_stock          | integer          | p_film_id integer, p_store_id integer, OUT p_film_count integer     | FUNCTION 
 public | get_customer_balance       | numeric          | p_customer_id integer, p_effective_date timestamp without time zone | FUNCTION 
 public | group_concat               | text             | text                                                                |  
 public | inventory_held_by_customer | integer          | p_inventory_id integer                                              | FUNCTION 
 public | inventory_in_stock         | boolean          | p_inventory_id integer                                              | FUNCTION 
 public | last_day                   | date             | timestamp without time zone                                         | FUNCTION 
 public | last_updated               | trigger          |                                                                     | FUNCTION 
 public | rewards_report             | USER-DEFINED     | min_monthly_purchases integer, min_dollar_amount_purchased numeric  | FUNCTION 
(10 rows)