Bug #114719 Incorrect results caused by different access types for an index

Description:
Run the following statements, in which the query Q1 is expected to return {0}. However, an empty result is returned.
If we enforce a different join order (the query Q2), the return result becomes correct.
I introspect their query plans, in which the access type in Q1 is ref and the access type in Q2 is index.

How to repeat:
CREATE TABLE t1 (c1 longtext);
CREATE TABLE t2 (c1 bit, KEY i0 (c1));
INSERT INTO t1 (c1) VALUES ('0');
INSERT INTO t2 (c1) VALUES (b'0');
-- Q1
SELECT /*+ JOIN_ORDER(t1,t2) */ t1.c1 FROM t1 NATURAL JOIN t2 USE INDEX (i0); -- {}, expected to be {0}
-- Q2
SELECT /*+ JOIN_ORDER(t2,t1) */ t1.c1 FROM t1 NATURAL JOIN t2 USE INDEX (i0); -- {0}

Suggested fix:
In this case, we should not use the access type ref, since the data types of join columns are different.

Hello John,

Thank you for the report and test case.
Verified as described.

regards,
Umesh