CREATE TABLE t1(c0 INT , c1 VARCHAR(100), c2 VARCHAR(100) , PRIMARY KEY(c0, c1)) engine=MyISAM;

CREATE TABLE t2(c0 INT);

CREATE TABLE t3(c0 BOOLEAN);

INSERT INTO t1 VALUES (2000, 'b', '');

INSERT INTO t1 VALUES (1000, '', 'a');

INSERT INTO t2 VALUES (3000);

mysql> SELECT * FROM t2 STRAIGHT_JOIN t1 ON (t1.c2 RLIKE t1.c1) WHERE t1.c0;

+------+------+----+------+

| c0   | c0   | c1 | c2   |

+------+------+----+------+

| 3000 | 1000 |    | a    |

+------+------+----+------+

mysql> SET STATEMENT optimizer_switch = 'mrr=on' FOR SELECT * FROM t2 STRAIGHT_JOIN t1 ON (t1.c2 RLIKE t1.c1) WHERE t1.c0;

Empty set (0.00 sec)

mysql> select version();

+---------------------------------------+

| version()                             |

+---------------------------------------+

| 11.1.2-MariaDB-1:11.1.2+maria~ubu2204 |

+---------------------------------------+

1 row in set (0.00 sec)