cassandra

cassandra五分钟入门

abloz 2015-06-05
2015-06-05

周海汉 2015.6.5

cassandra是apache开源的著名NoSQL数据库，使用起来非常简单，支持多台扩展，提供swift接口，类sql查询。开发方用285个node，测试达到每秒100万次写。性能还是挺可观的。

官网

http://cassandra.apache.org/download/

下载：

http://mirrors.cnnic.cn/apache/cassandra/2.1.5/apache-cassandra-2.1.5-bin.tar.gz

安装

下载的二进制直接解压。如果是deb或rpm安装的，配置文件在/etc/cassandra里。

在conf里配置log目录。

cassandra 2.1以上版本采用backlog记日志

zhh@apache-cassandra-2.1.5 % vi conf/logback.xml

修改下述目录为自己需要的目录，保证目录的可写。2.1以前的版本是写到/var/log或/var/lib目录的，可能没权限。

${cassandra.logdir}/system.log

缺省不修改则log存放当前安装目录的logs下面。

启动

启动cassandra，-f选项表示前台运行。如果没有-f，则用pkill -f cassandraDaemon

zhh@apache-cassandra-2.1.5 % ./bin/cassandra -f
…
INFO  08:31:37 Starting listening for CQL clients on localhost/127.0.0.1:9042...
INFO  08:31:37 Binding thrift service to localhost/127.0.0.1:9160
INFO  08:31:37 Listening for thrift clients...

客户端cqlsh:

zhh@apache-cassandra-2.1.5 % ./bin/cqlsh
Connected to Test Cluster at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.1.5 | CQL spec 3.2.0 | Native protocol v3]
Use HELP for help.
cqlsh> help

Documented shell commands:
===========================
CAPTURE      COPY  DESCRIBE  EXPAND  PAGING  SOURCE
CONSISTENCY  DESC  EXIT      HELP    SHOW    TRACING

CQL help topics:
================
ALTER                        CREATE_TABLE_OPTIONS  SELECT
ALTER_ADD                    CREATE_TABLE_TYPES    SELECT_COLUMNFAMILY
ALTER_ALTER                  CREATE_USER           SELECT_EXPR
ALTER_DROP                   DELETE                SELECT_LIMIT
ALTER_RENAME                 DELETE_COLUMNS        SELECT_TABLE
ALTER_USER                   DELETE_USING          SELECT_WHERE
ALTER_WITH                   DELETE_WHERE          TEXT_OUTPUT
APPLY                        DROP                  TIMESTAMP_INPUT
ASCII_OUTPUT                 DROP_COLUMNFAMILY     TIMESTAMP_OUTPUT
BEGIN                        DROP_INDEX            TRUNCATE
BLOB_INPUT                   DROP_KEYSPACE         TYPES
BOOLEAN_INPUT                DROP_TABLE            UPDATE
COMPOUND_PRIMARY_KEYS        DROP_USER             UPDATE_COUNTERS
CREATE                       GRANT                 UPDATE_SET
CREATE_COLUMNFAMILY          INSERT                UPDATE_USING
CREATE_COLUMNFAMILY_OPTIONS  LIST                  UPDATE_WHERE
CREATE_COLUMNFAMILY_TYPES    LIST_PERMISSIONS      USE
CREATE_INDEX                 LIST_USERS            UUID_INPUT
CREATE_KEYSPACE              PERMISSIONS
CREATE_TABLE                 REVOKE

cqlsh>
创建keyspace，相当于rds的database，用于存放table
cqlsh> create keyspace mykeyspace with replication={'class':'SimpleStrategy','replication_factor':1}
   ... ;
cqlsh> use mykeyspace;

创建表

cqlsh:mykeyspace> create table users(

              ... user_id int primary key,

              ... fname text,

              ... lname text

              ... );

插入数据

cqlsh:mykeyspace> insert into users (user_id,fname,lname) values(1,'john','smith');

cqlsh:mykeyspace> insert into users (user_id,fname,lname) values(2,'三','张');

cqlsh:mykeyspace> insert into users (user_id,fname,lname) values(1,'john','smith');

cqlsh:mykeyspace> insert into users (user_id,fname,lname) values(3,'john','smith');

cqlsh:mykeyspace> select * from users;

 user_id | fname | lname

---------+-------+-------

       1 |  john | smith

       2 |    三 |    张

       3 |  john | smith

(3 rows)

cqlsh:mykeyspace>

直接用没有索引的字段查询报错：

cqlsh:mykeyspace> select * from users where lname='smith';

InvalidRequest: code=2200 [Invalid query] message="No secondary indexes on the restricted columns support the provided operators: "

cqlsh:mykeyspace> select * from users where user_id='2';

InvalidRequest: code=2200 [Invalid query] message="Invalid STRING constant (2) for "user_id" of type int"

cqlsh:mykeyspace> select * from users where user_id=2;

 user_id | fname | lname

---------+-------+-------

       2 |    三 |    张

(1 rows)

在姓氏上建索引，再查询不再报错

cqlsh:mykeyspace> create index on users(lname);

cqlsh:mykeyspace> select * from users where lname='张';

 user_id | fname | lname

---------+-------+-------

       2 |    三 |    张

(1 rows)

cqlsh:mykeyspace> select * from users where lname='smith';

 user_id | fname | lname

---------+-------+-------

       1 |  john | smith

       3 |  john | smith

(2 rows)

cqlsh:mykeyspace> ^D

ctrl+D 结束

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