Cassandra 地图中的重复键

Question

Cassandra地图实现是Map还是MultiMap？换句话说，Cassandra 是否允许映射类型中的重复键？基于this example，如果我调用

UPDATE cycling.cyclist_teams SET teams = teams + {2009 : 'First team'} WHERE id = 5b6962dd-3f90-4c93-8f61-eabfa4a803e2;

然后

UPDATE cycling.cyclist_teams SET teams = teams + {2009 : 'Second team'} WHERE id = 5b6962dd-3f90-4c93-8f61-eabfa4a803e2;

那么数据库将如下所示：A)

teams[2009]: 'Second team'

或者这个：B)

teams[2009]: 'First team'
teams[2009]: 'Second team'

Answer 1

这个documentation说的很清楚：

A map relates one item to another with a key-value pair. For each key, only one value may exist, and duplicates cannot be stored. Both the key and the value are designated with a data type.

也就是说，值会被覆盖，就像java HashMap一样。结果将是 {2009 : 'Second team'}