Return to Question

=> SELECT CAST('1962-05-02 00:00' AS TIMESTAMP) = CAST('1962-05-02 00:00:00' AS TIMESTAMP);
 ?column? 
----------
 t
(1 row)

=> SELECT CAST('1962-05' AS TIMESTAMP) = CAST('1962-05-02' AS TIMESTAMP);
 ?column? 
----------
 t
(1 row)

=> SELECT CAST('1964-05-02 00:00' AS TIMESTAMP) = CAST('1964-05-02 00:00:00' AS TIMESTAMP);
 ?column? 
----------
 t
(1 row)

=> SELECT CAST('1964-05' AS TIMESTAMP) = CAST('1964-05-02' AS TIMESTAMP);
 ?column? 
----------
 t
(1 row)

The meaning of 1964-05 in ISO 8601 includes the more-precise values 1964-05-02 and 1964-05-02 18:27 and 1964-05-23. So those should all compare equal.