text: --
  -- num_nulls()
  --
  
  SELECT num_nonnulls(NULL);
  SELECT num_nonnulls('1');
  SELECT num_nonnulls(NULL::text);
  SELECT num_nonnulls(NULL::text, NULL::int);
  SELECT num_nonnulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL);
  SELECT num_nonnulls(VARIADIC '{1,2,NULL,3}'::int[]);
  SELECT num_nonnulls(VARIADIC '{"1","2","3","4"}'::text[]);
  SELECT num_nonnulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i));
  
  SELECT num_nulls(NULL);
  SELECT num_nulls('1');
  SELECT num_nulls(NULL::text);
  SELECT num_nulls(NULL::text, NULL::int);
  SELECT num_nulls(1, 2, NULL::text, NULL::point, '', int8 '9', 1.0 / NULL);
  SELECT num_nulls(VARIADIC '{1,2,NULL,3}'::int[]);
  SELECT num_nulls(VARIADIC '{"1","2","3","4"}'::text[]);
  SELECT num_nulls(VARIADIC ARRAY(SELECT CASE WHEN i <> 40 THEN i END FROM generate_series(1, 100) i));
  
  -- special cases
  SELECT num_nonnulls(VARIADIC NULL::text[]);
  SELECT num_nonnulls(VARIADIC '{}'::int[]);
  SELECT num_nulls(VARIADIC NULL::text[]);
  SELECT num_nulls(VARIADIC '{}'::int[]);
  
  -- should fail, one or more arguments is required
  SELECT num_nonnulls();
  SELECT num_nulls();
  
  --
  -- Test adding a support function to a subject function
  --
  
  CREATE FUNCTION my_int_eq(int, int) RETURNS bool
    LANGUAGE internal STRICT IMMUTABLE PARALLEL SAFE
    AS $$int4eq$$;
  
  -- By default, planner does not think that's selective
  EXPLAIN (COSTS OFF)
  SELECT * FROM tenk1 a JOIN tenk1 b ON a.unique1 = b.unique1
  WHERE my_int_eq(a.unique2, 42);
  
  -- With support function that knows it's int4eq, we get a different plan
  ALTER FUNCTION my_int_eq(int, int) SUPPORT test_support_func;
  
  EXPLAIN (COSTS OFF)
  SELECT * FROM tenk1 a JOIN tenk1 b ON a.unique1 = b.unique1
  WHERE my_int_eq(a.unique2, 42);
  
  -- Also test non-default rowcount estimate
  CREATE FUNCTION my_gen_series(int, int) RETURNS SETOF integer
    LANGUAGE internal STRICT IMMUTABLE PARALLEL SAFE
    AS $$generate_series_int4$$
    SUPPORT test_support_func;
  
  EXPLAIN (COSTS OFF)
  SELECT * FROM tenk1 a JOIN my_gen_series(1,1000) g ON a.unique1 = g;
  
  EXPLAIN (COSTS OFF)
  SELECT * FROM tenk1 a JOIN my_gen_series(1,10) g ON a.unique1 = g;
  