Caveats

Equality Comparison

Equality and ordering comparisons on JSON values are based on their raw physical text, not on their logical content. Two JSON values with identical logical content are treated as different whenever their text differs in whitespace, number formatting, or object key order.

The following query shows that JSON comparison is purely textual, so logically equivalent values are treated as not equal when their physical text differs. It also shows the subscript operator ([...]) extracting an array element by position and an object field by key:

Query

SELECT    '[1,2]'::JSON = '[1, 2]'::JSON                 AS whitespace_differs,    -- f: the extra space is part of the physical text    '1'::JSON = '1.0'::JSON                        AS number_format_differs, -- f: 1 and 1.0 are not textually equal    '{"a":1,"b":2}'::JSON = '{"b":2,"a":1}'::JSON  AS key_order_differs,     -- f: object key order is physical    ('[10,20,30]'::JSON)[1]                        AS element_by_index,      -- 20: array subscript extracts by position    ('{"a":42}'::JSON)['a']                        AS field_by_key;          -- 42: object subscript extracts by key

Result

 whitespace_differs | number_format_differs | key_order_differs | element_by_index | field_by_key--------------------+-----------------------+-------------------+------------------+-------------- f                  | f                     | f                 |               20 |           42