Partition ordering for multi-column keys is incorrect

[jcjones]

Given the partition layout:

PARTITION `p_20220413` VALUES LESS THAN (2300107903,2178845982) ENGINE = InnoDB,
 PARTITION `p_20220513` VALUES LESS THAN (2517982016,2390412410) ENGINE = InnoDB,
 PARTITION `p_20220508` VALUES LESS THAN (2661645087,2536435703) ENGINE = InnoDB,
 PARTITION `p_20220525` VALUES LESS THAN (2805308158,2682458996) ENGINE = InnoDB,
 PARTITION `p_20220611` VALUES LESS THAN (7882495694,7856340600) ENGINE = InnoDB,
 PARTITION `p_20230519` VALUES LESS THAN (10790547177,11048018089) ENGINE = InnoDB,
 PARTITION `p_20230724` VALUES LESS THAN (95233456870,97348306298) ENGINE = InnoDB,
 PARTITION `p_20230823` VALUES LESS THAN (MAXVALUE,MAXVALUE) ENGINE = InnoDB

and the position (8236363504, 6096301914), current versions of Partition Manager will assume the "current" partition is p_20220611. However, that is not correct: MySQL writes into the next partition if any of those values moves beyond the limits of a partition, not if all do.

In reality, partition p_20230519 is the "current" one.

To quote from the documentation:

With RANGE COLUMNS, a row matches a partition if all row values are less than specified values. The first partition that matches row values will be used.