Cassandra 使用笔记

环境安装

1. 添加仓库配置 vim /etc/yum.repos.d/cassandra.repo 文件, 追加如下内容：

[cassandra]
name=Apache Cassandra
baseurl=https://www.apache.org/dist/cassandra/redhat/311x/
gpgcheck=1
repo_gpgcheck=1
gpgkey=https://www.apache.org/dist/cassandra/KEYS

2. 安装基础服务

yum install cassandra -y

3. 配置集群

默认配置被安装到 /etc/cassandra/conf 目录下，在此配置 conf/cassandra.yaml 文件即可：

cluster_name: 'DBACluster'
num_tokens: 256
seed_provider:
    - class_name: org.apache.cassandra.locator.SimpleSeedProvider
      parameters:
          - seeds: "172.xxx.xxx.110,172.xxx.xxx.111,172.xxx.xxx.112"         # 集群 ip 列表
start_rpc: true
listen_address: 172.xxx.xxx.110      # 本机 ip
rpc_address: 172.xxx.xxx.110         # 本机 ip
endpoint_snitch: SimpleSnitch

注 关键性的修改如上所示，其余内容可以不必修改，维持现状即可。

4. 启动服务

这里使用 service 命令进行启动，也可以使用 systemctl 需要 先执行下 systemctl daemon-reload 否则找不到服务。

service cassandra start

简单使用

查看节点状态

[root@localhost conf]$ nodetool status
Datacenter: datacenter1
=======================
Status=Up/Down
|/ State=Normal/Leaving/Joining/Moving
--  Address         Load       Tokens       Owns (effective)  Host ID                               Rack
UN  172.xxx.xxx.112  69.91 KiB  256          69.7%             b094898b-231a-4354-9a93-026b83b26200  rack1
UN  172.xxx.xxx.111  69.92 KiB  256          66.8%             0be19954-b3dc-496b-a153-1b6b611ff889  rack1
UN  172.xxx.xxx.110  103.67 KiB  256          63.4%             553d2de4-3f30-49c2-82e7-b48e092fbffd  rack1

基础操作

使用 cqlsh 命令作为 cassandra 默认客户端程序，如下操作：

[root@localhost conf]# cqlsh 172.xxx.xxx.110
Connected to DBACluster at 172.xxx.xxx.110:9042.
[cqlsh 5.0.1 | Cassandra 3.11.4 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.
cqlsh>

1. 查询当前属性

cqlsh> SELECT cluster_name, listen_address FROM system.local;

 cluster_name | listen_address
--------------+----------------
   DBACluster | 172.xxx.xxx.110

(1 rows)

2. 查看版本信息

cqlsh> SHOW VERSION
[cqlsh 5.0.1 | Cassandra 3.11.4 | CQL spec 3.4.4 | Native protocol v4]

3. 查看主机信息

cqlsh> SHOW HOST
Connected to DBACluster at 172.xxx.xxx.110:9042.

4. 创建用户

• 开启密码保护

修改 cassandra.yaml 文件，将

authenticator: AllowAllAuthenticator
authorizer: AllowAllAuthorizer

修改为

authenticator: PasswordAuthenticator
authorizer: CassandraAuthorizer

注 此时默认用户为 cassandra/cassandra

• 创建用户

[root@localhost conf]# cqlsh 172.xxx.xxx.110 -ucassandra -pcassandra
Connected to DBACluster at 172.xxx.xxx.110:9042.
[cqlsh 5.0.1 | Cassandra 3.11.4 | CQL spec 3.4.4 | Native protocol v4]
Use HELP for help.
cqlsh> CREATE USER 用户名 WITH PASSWORD '密码' SUPERUSER ;

• 删除用户

cqlsh> DROP USER cassandra ;

代码中设置密码如下：

Cluster cluster = Cluster.builder()
                 .addContactPoint("172.xxx.xxx.110")
                 .withCredentials("用户名", "密码")
                 .build();

权限信息

权限管理这块数据保存在 system_auth 里面，如下所示

cqlsh> desc keyspace system_auth

CREATE KEYSPACE system_auth WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}  AND durable_writes = true;

CREATE TABLE system_auth.resource_role_permissons_index (
    resource text,
    role text,
    PRIMARY KEY (resource, role)
) 

CREATE TABLE system_auth.role_permissions (
    role text,
    resource text,
    permissions set<text>,
    PRIMARY KEY (role, resource)
) 

CREATE TABLE system_auth.role_members (
    role text,
    member text,
    PRIMARY KEY (role, member)
) 

CREATE TABLE system_auth.roles (
    role text PRIMARY KEY,
    can_login boolean,
    is_superuser boolean,
    member_of set<text>,
    salted_hash text
)

• 查看权限信息

cqlsh> use system_auth;
cqlsh:system_auth> select * from resource_role_permissons_index;

 resource | role
----------+------

(0 rows)
cqlsh:system_auth> select * from role_permissions;

 role | resource | permissions
------+----------+-------------

(0 rows)
cqlsh:system_auth> select * from role_permissions;

 role | resource | permissions
------+----------+-------------

(0 rows)
cqlsh:system_auth> select * from roles;

 role      | can_login | is_superuser | member_of | salted_hash
-----------+-----------+--------------+-----------+-------------------------------
 cassandra |      True |         True |      null | $2a$10...RhFCCKQwT6wNyucgANW

(1 rows)

注 参考 用户密码设置

keyspace 相关

• 查看 keyspace 列表

cqlsh> describe keyspaces;

system_schema  system              xxxx 
system_auth    system_distributed  system_traces

• 查看 keyspace 具体详情

cqlsh> desc keyspace xxxx

CREATE KEYSPACE xxxx WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '3'}  AND durable_writes = true;

CREATE TABLE xxxx.t (
    pk int,
    a int,
    b int,
    c int,
    PRIMARY KEY (pk, a)
)

• 创建/使用 keyspace

# 创建  `keyspace` 
cqlsh> CREATE KEYSPACE knet WITH REPLICATION = { 'class' : 'SimpleStrategy', 'replication_factor' : 1 };
# 使用  `keyspace` 
cqlsh> use knet ;
# 查看  `keyspace` 中所有表列表
cqlsh:knet> desc tables;
todayscore  t
# 查看表结构
cqlsh:knet> desc table todayscore;

注 Replication Factor : 复制因数。 表示一份数据在一个DC 之中包含几份。常用奇数~ 比如我们项目组设置的replication_factor=3
注 Replica placement strategy : 复制策略。 默认的是SimpleStrategy. 如果是单机架、单数据中心的模式，保持使用SimpleStrtegy即可。