-- maxItems validation
-- shorter is valid
SELECT is_jsonb_valid('{"maxItems":2}', '[1]');
 is_jsonb_valid 
----------------
 t
(1 row)

-- exact length is valid
SELECT is_jsonb_valid('{"maxItems":2}', '[1,2]');
 is_jsonb_valid 
----------------
 t
(1 row)

-- too long is invalid
SELECT is_jsonb_valid('{"maxItems":2}', '[1,2,3]');
 is_jsonb_valid 
----------------
 f
(1 row)

-- ignores non-arrays
SELECT is_jsonb_valid('{"maxItems":2}', '"foobar"');
 is_jsonb_valid 
----------------
 t
(1 row)