/* Select all rows from left table which aren't in right table.

   SELECT  l.*
   FROM    t_left l
   LEFT JOIN t_right r
   ON      r.value = l.value
   WHERE   r.value IS NULL
 */

/*
   TODO Add another layer of JOINs to show the value where name='Received' for
   the missing hashes.  Maybe we can parse dates from there.
 */
SELECT
    l.hash, r.value
FROM
    original l
LEFT JOIN (
    SELECT
        hash,
        value
    FROM
        search_header
    WHERE
        name = 'Date'
    ) r
ON
    r.hash = l.hash
WHERE
    r.hash IS NULL
;