pg_functions.sql

-- Create the view pg_functions for PostgreSQL 11 or newer
CREATE OR REPLACE VIEW pg_functions AS
SELECT pg_namespace.nspname AS schema_name
  , pg_proc.proname AS function_name
  , pg_catalog.pg_get_function_result(pg_proc.oid) AS returning_data_type
  , pg_catalog.pg_get_function_arguments(pg_proc.oid) AS parameters
  , CASE
      WHEN pg_proc.prokind = 'a' THEN
        'aggregate'
      WHEN pg_proc.prokind = 'w' THEN
        'window'
      WHEN pg_proc.prokind = 'f' THEN
        'function'
      WHEN pg_proc.prorettype = 'pg_catalog.trigger'::pg_catalog.regtype THEN
        'trigger'
      ELSE
        'unknown'
    END as function_type
  , pg_description.description AS function_comment
FROM pg_catalog.pg_proc
  LEFT OUTER JOIN pg_catalog.pg_namespace
    ON pg_proc.pronamespace = pg_namespace.oid
  LEFT OUTER JOIN pg_catalog.pg_description
    ON pg_proc.oid = pg_description.objoid
WHERE pg_catalog.pg_function_is_visible(pg_proc.oid)
  AND pg_namespace.nspname NOT IN ('pg_catalog', 'information_schema')
ORDER BY schema_name
  , function_name
  , parameters
;

COMMENT ON VIEW pg_functions IS 'The view returns all functions of the current database, excluding those in the schema pg_catalog and information_schema';

-- Source: https://github.com/sjstoelting/pgsql-tweaks/blob/main/sql/view_pg_functions.sql