MariaDB [test]> set statement optimizer_switch = 'join_cache_incremental=on' for SELECT t1.c1 FROM t2 CROSS JOIN t1 ON TRUE RIGHT JOIN t0 ON t1.c0 IN (t1.c0 REGEXP t1.c0);

+------+

| c1   |

+------+

|    3 |

|    3 |

+------+

2 rows in set, 6 warnings (0.001 sec)

MariaDB [test]> show warnings;

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

| Level   | Code | Message                                                                                                                                   |

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

| Warning | 1292 | Truncated incorrect DECIMAL value: 'b                                                                                                   ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

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

6 rows in set (0.000 sec)

MariaDB [test]> set statement optimizer_switch = 'join_cache_incremental=off' for SELECT t1.c1 FROM t2 CROSS JOIN t1 ON TRUE RIGHT JOIN t0 ON t1.c0 IN (t1.c0 REGEXP t1.c0);

+------+

| c1   |

+------+

|    3 |

| NULL |

+------+

2 rows in set, 5 warnings (0.001 sec)

MariaDB [test]> show warnings;

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

| Level   | Code | Message                                                                                                                                   |

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

| Warning | 1292 | Truncated incorrect DECIMAL value: 'b                                                                                                   ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: 'b                                                                                                   ' |

| Warning | 1292 | Truncated incorrect DECIMAL value: '                                                                                                    ' |

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

5 rows in set (0.000 sec)