OLAP系列之分析型数据库clickhouse集群扩缩容(四)

一、集群缩容

1.1 下线节点

步骤：
1.对外停止服务
2.转移数据
3.修改剩余节点配置
4.通知客户端修改节点列表

# 修改90，91服务器配置文件
vim /etc/clickhouse-server/conf.d/metrika.xml 中注释掉第3个shard
    <remote_servers>
        <clickhouse_cluster_3shards_1replicas>
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.91</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.90</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
<!--  注销掉
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.88</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
-->
        </clickhouse_cluster_3shards_1replicas>
    </remote_servers>

# 查询集群
aliyun-47-122-26-25 :) select * from system.clusters;

SELECT *
FROM system.clusters

Query id: 4a1a0d43-9c19-4424-9c87-338b081e8813

┌─cluster──────────────────────────────┬─shard_num─┬─shard_weight─┬─replica_num─┬─host_name─────┬─host_address──┬─port─┬─is_local─┬─user────┬─default_database─┬─errors_count─┬─slowdowns_count─┬─estimated_recovery_time─┐
│ clickhouse_cluster_3shards_1replicas │         1 │            1 │           1 │ 192.168.12.91 │ 192.168.12.91 │ 9000 │        1 │ default │                  │            0 │               0 │                       0 │
│ clickhouse_cluster_3shards_1replicas │         2 │            1 │           1 │ 192.168.12.90 │ 192.168.12.90 │ 9000 │        0 │ default │                  │            0 │               0 │                       0 │
└──────────────────────────────────────┴───────────┴──────────────┴─────────────┴───────────────┴───────────────┴──────┴──────────┴─────────┴──────────────────┴──────────────┴─────────────────┴─────────────────────────┘

2 rows in set. Elapsed: 0.001 sec. 

# 将下线节点的数据转移到其它节点，迁移方式可以使用以下方式：
clickhouse-client --password
use test_log
 :) insert into test_local select * from remote('192.168.12.88','test_log','test_local','default','password');

Query id: 7c2a0285-0323-4498-82b4-1adadc90aa18

Ok.

0 rows in set. Elapsed: 0.007 sec. 

test_log:库名       default：账号
test_local:表名     password:密码

# 如果数据库过大可以，可以将数据分别存储在其余2台集群上
# 在集群1上执行下面的sql，将集群3的部分数据写到集群3的本地表中
insert into test_log select * from remote('192.168.12.88:9000','test_log','user','password') where id % 2 = 0;
# 在集群2执行下面的sql，将集群3的部分数据写到集群2的本地表中
insert into test_log select * from remote('192.168.12.88:9000','test_log','user','password') where id % 2 = 1;

SELECT *
FROM test_all
Query id: 2a3627db-c64b-45a1-b3be-1868dff84f90
┌─id─┬─name──────┐
│  1 │ zhangsan  │
│  2 │ lisi      │
│  7 │ yw        │
│  8 │ xc        │
│  5 │ zhangquan │
│  6 │ lihua     │
│ 11 │ bb        │
│ 12 │ acca      │
└────┴───────────┘
┌─id─┬─name───┐
│  3 │ wangm  │
│  4 │ lijing │
│  9 │ cx     │
│ 10 │ aa     │
│ 13 │ kkkk   │
└────┴────────┘
13 rows in set. Elapsed: 0.003 sec.

二、集群扩容

# 原配置
        <clickhouse_cluster_3shards_1replicas>
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.91</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.90</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
        </clickhouse_cluster_3shards_1replicas>

# 新增节点步骤
1.新节点安装clickhouse
2.在新节点新增相关本地表
3.修改旧节点配置
4.通知客户端修改节点列表

# 1.修改配置/etc/clickhouse-server/config.d/metrika.xml，编辑新节点，新增：
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.88</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>

# 2.在新节点新建该集群相关本地表
# 注意和其它节点数据库表面引擎都要一样

# 3.修改集群旧节点的config.xml配置，加上新节点

修改完成后，clickhouse会自动感知到config文件变化，修改的内容会立刻生效

# 4.通知客户端更新节点列表

三、扩容后数据的均匀分布

# 通过设置集群权重，让后面的数据优先写入新节点

        <clickhouse_cluster_3shards_1replicas>
            <shard>
                <weight>1</weight>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.91</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
            <shard>
                <weight>1</weight>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.90</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
            <shard>
                <weight>99</weight>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.12.88</host>
                    <port>9000</port>
                    <user>default</user>
                    <password>PeQLg45tJcxZk</password>
                </replica>
            </shard>
        </clickhouse_cluster_3shards_1replicas>