--source include/have_innodb.inc

CREATE TABLE t0(c0 int, key (c0)) ENGINE=INNODB;

INSERT INTO t0 VALUES (null);

SET optimizer_switch = 'not_null_range_scan=off';

select c0  from t0 where 1 <> locate(1,0,c0); 

SET optimizer_switch = 'not_null_range_scan=on';

select c0  from t0 where 1 <> locate(1,0,c0);

alter table t0 drop index c0;

select c0  from t0 where 1 <> locate(1,0,c0);

drop table t0;

MariaDB [test]> CREATE TABLE t0(c0 int, key (c0)) ENGINE=INNODB;

Query OK, 0 rows affected (0,038 sec)

MariaDB [test]> INSERT INTO t0 VALUES (null);

Query OK, 1 row affected (0,002 sec)

MariaDB [test]> SET optimizer_switch = 'not_null_range_scan=off';

Query OK, 0 rows affected (0,000 sec)

MariaDB [test]> select c0  from t0 where 1 <> locate(1,0,c0); 

+------+

| c0   |

+------+

| NULL |

+------+

1 row in set (0,000 sec)

MariaDB [test]> SET optimizer_switch = 'not_null_range_scan=on';

Query OK, 0 rows affected (0,000 sec)

MariaDB [test]> select c0  from t0 where 1 <> locate(1,0,c0);

Empty set (0,000 sec)

MariaDB [test]> explain extended select c0  from t0 where 1 <> locate(1,0,c0);

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

| id   | select_type | table | type  | possible_keys | key  | key_len | ref  | rows | filtered | Extra                    |

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

|    1 | SIMPLE      | t0    | range | NULL          | c0   | 5       | NULL | 1    |   100.00 | Using where; Using index |

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

1 row in set, 1 warning (0,001 sec)

Note (Code 1003): select `test`.`t0`.`c0` AS `c0` from `test`.`t0` where 1 <> locate(1,0,`test`.`t0`.`c0`)

MariaDB [test]> alter table t0 drop index c0;

Query OK, 0 rows affected (0,031 sec)

Records: 0  Duplicates: 0  Warnings: 0

MariaDB [test]> select c0  from t0 where 1 <> locate(1,0,c0);

+------+

| c0   |

+------+

| NULL |

+------+

1 row in set (0,001 sec)