Cassandra 入门

一. 基本概念

1. Primary Key, Partition Key, Clustering Key

以下面的Table为例子：

create table sample(

      k_part_one text,

      k_part_two int,

      k_clust_one text,

      k_clust_two int,

      k_clust_three uuid,

      data text,

      PRIMARY KEY((k_part_one,k_part_two),k_clust_one, k_clust_two, k_clust_three)     

  ) with CLUSTERING ORDER BY (k_clust_one DESC, k_clust_two ASC);

Primary Key=Partition Key + Clustering Key， Partition Key是(k_part_one,k_part_two)，Clustering Key是k_clust_one, k_clust_two, k_clust_three。

Partition Key决定了数据存储在集群的哪个节点，Primary Key决定数据在当前节点的排序。

2. 集合类型

1) set      如：set<text>,  有序集合 {'f@baggins.com', 'baggins@gmail.com'}

2) list      如：list<text>,  数组 ['rivendell', 'rohan' ]

3) map   如：map<timestamp, text>, 字典 { '2013-9-22 12:01' : 'birthday wishes to Bilbo', '2013-10-1 18:00': 'Check into Inn of Pracing Pony'}