java - 如何在地图上编写聚合函数根据键值计算 MIN、MAX 和 AVG

Question

我在 cassandra 中有 MAP 类型的元素 cloumn

elements = [{"a":10,"b":12,"c":13,"d":14},{"a":2,"b":1,"c":5,"d":19},{"a":5,"b":4,"c":13,"d":4},{"a":140,"b":1,"c":4,"d":14}]

我想在 java 中编写一个聚合函数，找到 Map Keys 的 min max，结果将是。

[{a "min": 2, "max": 140},{b "min": 1, "max": 5},{c "min": 4, "max": 13},{d "min": 4, "max": 19}]

我从来没有写过这些东西。需要帮忙。

标签： javacassandra