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)

)withCLUSTERING ORDER BY (k_clust_oneDESC,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_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'}

3. 自定义类型(UDT)

CREATE TYPE mykeyspace.address (
street text,
city text,
zip_code int,
phones set<text>
);

二. 安装

下面以在windows 7 x64 安装Cassandra 2.1.14为例

1) 下载JDK并安装至C:\Program Files\Java\jdk1.8.0_91

http://download.oracle.com/otn-pub/java/jdk/8u91-b15/jdk-8u91-windows-x64.exe?AuthParam=1465374689_e7b7ab5575db24a9221c618360f4fa5d

2) 下载apache cassandra 2.1.14,并解压缩到D:\apache-cassandra-2.1.14

http://mirror.bit.edu.cn/apache/cassandra/2.1.14/apache-cassandra-2.1.14-bin.tar.gz

3) 修改D:\apache-cassandra-2.1.14\bin下的两个配置文件

a.cassandra.bat

在@REMlimitations under the License. 行下添加下面两行

set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_91
set CASSANDRA_HOME=D:\apache-cassandra-2.1.14

b.cassandra.in.bat

在@REMlimitations under the License.行下添加下面两行

set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_91
set CASSANDRA_HOME=D:\apache-cassandra-2.1.14

4) 在D:\apache-cassandra-2.1.14\下创建以下目录

data

data\data

data\commitlog

也可以通过修改conf\cassandra.yaml配置文件，将目录创建在其它地方。

# Directories where Cassandra should store data on disk. Cassandra
# will spread data evenly across them,subject to the granularity of
# the configured compaction strategy.
# If not set,the default directory is $CASSANDRA_HOME/data/data.
# data_file_directories:
# - /var/lib/cassandra/data

# commit log. when running on magnetic HDD,this should be a
# separate spindle than the data directories.
# If not set,the default directory is $CASSANDRA_HOME/data/commitlog.
# commitlog_directory: /var/lib/cassandra/commitlog