--source include/force_myisam_default.inc
--source include/have_myisam.inc

--disable_warnings
DROP TABLE IF EXISTS t1;
--enable_warnings

CREATE TABLE t1 (
    tx TEXT CHARACTER SET utf8mb3 NULL,
    pk INTEGER AUTO_INCREMENT,
    PRIMARY KEY (pk)
) ENGINE=myisam;

INSERT INTO t1 VALUES
(
    'valid-string',
    NULL
)
,
(
    UNHEX('FF'),
    NULL
)
;

SELECT pk,OCTET_LENGTH(tx),LENGTH(tx) FROM t1; 

SELECT tx FROM t1 ORDER BY tx DESC;

DROP TABLE t1;