【Clickhouse】Clickhouse-copier数据复制-迁移案例

原创已于 2023-03-24 15:44:25 修改 · 置顶 · 6.1k 阅读

15 ·

CC 4.0 BY-SA版权

文章标签：

#数据库 #clickhouse #ck-copier

于 2021-12-29 15:24:34 首次发布

clickhouse 专栏收录该内容

5 篇文章

订阅专栏

Clickhouse-copier数据复制-迁移案例

2022年03月04日更新
背景
方案调研

2022年03月04日更新

Clickhouse-copier支持将数据从一个群集中的表复制到另一个（或相同）群集中的表。

        <!-- 源集群配置信息（写入源表存在的分片以及节点即可，不需要把整个集群的节点全写上） -->
        <src_manyun_ch_cluster>
        
        <!-- 目标集群配置信息（写入目标存在的分片以及节点即可，不需要把整个集群的节点全写上）-->
        <des_manyun_ch_cluster>

背景

因新环境上线，需要从旧环境中迁移数据至新环境。

方案调研

方案一：拷贝数据目录

先观察一下 ClickHouse 在文件系统上的目录结构（配置文件 /ect/clickhouse-server/config.xml 里面配置的），为了便于查看，只保留了 data 和 metadata 目录。

data 目录里保存的是数据，每个数据库一个目录，内部每个表一个子目录。
metadata 目录里保存的是元数据，即数据库和表结构。其中
- database.sql 是创建数据库的 DDL（ATTACH DATABASE default ENGINE = Ordinary）
- database/table.sql 是建表的 DDL (ATTACH TABLE …).
  这里的 DDL 使用的是 ATTACH 语句，基于这个信息，直接把 data 和 metadata 目录（要排除 system）复制到新集群，即可实现数据迁移。用一个小表做测试，验证可行。

操作流程

在源集群的硬盘上打包好对应数据库或表的 data 和 metadata 数据
拷贝到目标集群对应的目录
重启 clickhouse-server

方案二：使用 remote 表函数

ClickHouse 除了查询常规的表，还能使用表函数来构建一些特殊的「表」，其中 remote 函数可用于查询另一个 ClickHouse 的表。
使用方式很简单:

SELECT * FROM remote(‘addresses_expr’, db, table, ‘user’, ‘password’) LIMIT 10;
因此，可以借助这个功能实现数据迁移：
INSERT INTO <local_database>.<local_table> SELECT * FROM remote(‘remote_clickhouse_addr’, <remote_database>, <remote_table>, ‘<remote_user>’, ‘<remote_password>’)

操作流程

在源集群的 system.tables 表查询出数据库、表、DDL、分区、表引擎等信息
在目标集群上，运行 DDL 创建表，然后运行上述迁移语句复制数据
遍历所有表，执行 2

方案三：Clickhouse-copier(已采用)

clickhouse-copier是官方的数据迁移工具，用于多个集群之间的数据迁移。
官网文档配置

Clickhouse-copier的工作流介绍

读取的配置文件有两个，一个是zk的zookeeper.xml配置，一个是保存在zk中迁移任务的task.xml配置。

连接到zk并且接收:
- 复制作业。
- 复制作业的状态。
读取写入到到zk的task.xml执行工作。
- clickhouse-copier 跟踪zk中 /task/path/description 并应用它们。注：description中的内容为task.xml的配置
- 根据每个正在运行的进程都会选择源集群的“最接近的”分片，然后将数据复制到目标集群，并在必要时重新分片数据。

配置

zookeeper.xml
在装有clickhouse-copier服务器自定义路径中配置zookeeper.xml
该配置文件由日志级别信息和源端集群zk的配置信息两部分组成。此配置文件用于clickhouse-copier启动。

<yandex>
    <logger>
        <level>trace</level>
        <size>100M</size>
        <count>3</count>
    </logger>
    <zookeeper>
        <node index="1">
                <host>zkip1</host>
                <port>12181</port>
        </node>
        <node index="2">
                <host>zkip2</host>
                <port>12181</port>
        </node>
        <node index="3">
                <host>zkip3</host>
                <port>12181</port>
        </node>
    </zookeeper>
</yandex>

task.xml

该配置文件是用于clickhouse-copier运行前写入zk节点上的。


<yandex>
    <remote_servers>
        <!-- 源集群配置信息（写入源表存在的分片以及节点即可，不需要把整个集群的节点全写上） -->
        <src_manyun_ch_cluster>
        	  <!-- 分片1 -->
            <shard>
               <internal_replication>true</internal_replication>
                		<!-- 副本1 -->
                    <replica>
                        <host>src_ck_ip1</host>
                        <port>9000</port>
                        <user>root</user>
                        <password>pass</password>
                    </replica>
                    <!-- 副本2 -->
                    <replica>
                        <host>src_ck_ip2</host>
                        <port>9000</port>
                        <user>root</user>
                        <password>pass</password>
                    </replica>
            </shard>
            <!-- 分片2 -->
            <shard>
                <internal_replication>true</internal_replication>
                    <replica>
                        <host>src_ck_ip3</host>
                        <port>9000</port>
                        <user>root</user>
                        <password>pass</password>
                    </replica>
                    <replica>
                        <host>src_ck_ip4</host>
                        <port>9000</port>
                        <user>root</user>
                        <password>pass</password>
                    </replica>
            </shard>
        </src_manyun_ch_cluster>
        <!-- 目标集群配置信息（写入目标存在的分片以及节点即可，不需要把整个集群的节点全写上）-->
        <des_manyun_ch_cluster>
        	<!-- 分片1 -->
          <shard>
            <internal_replication>true</internal_replication>
            		<!-- 副本1 -->
                <replica>
                    <host>des_ck_ip1</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
                <!-- 副本2 -->
                <replica>
                    <host>des_ck_ip2</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
          </shard>
          <!-- 分片2 -->
          <shard>
            <internal_replication>true</internal_replication>
                <replica>
                    <host>des_ck_ip3</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
                <replica>
                    <host>des_ck_ip4</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
          </shard>
          <!-- 分片3 -->
          <shard>
            <internal_replication>true</internal_replication>
                <replica>
                    <host>des_ck_ip5</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
                <replica>
                    <host>des_ck_ip6</host>
                    <port>9000</port>
                    <user>root</user>
                    <password>pass</password>
                </replica>
          </shard>
        </des_manyun_ch_cluster>
    </remote_servers>
     <!-- copier最大进程数 -->
    <max_workers>8</max_workers>
    <!-- 同步表信息 -->
    <tables>
         <!-- table_test_job为自定义分类标签,仅用来区分不同的表同步任务 -->
        <table_test_job>
            <!-- pull信息,源表位置 -->
            <cluster_pull>src_manyun_ch_cluster</cluster_pull>
            <database_pull>src库名</database_pull>
            <table_pull>src表名</table_pull>
            <!-- push信息，目标表位置 -->
            <cluster_push>des_manyun_ch_cluster</cluster_push>
            <database_push>des库名</database_push>
            <table_push>des表名</table_push>
            <!-- 目的表的engine信息，目标集群没有表的情况下，会根据此engine配置创建表 -->
            <engine>            ENGINE=ReplicatedMergeTree('/clickhouse/tables/{shard}/库名/表名', '{replica}')
            PARTITION BY toYYYYMM(time)
            ORDER BY (device_guid, point_code, time, device_type)
            SETTINGS index_granularity = 8192
            </engine>
            <!-- 用于向目标集群插入数据的分片键，插入到目标的指定分片中 -->
            <sharding_key>02</sharding_key>
            <!-- 查询源数据时可以添加的过滤条件 -->
            <!--
                <where_condition> CounterID != 0 </where_condition>
              -->
            <!-- 指定同步的具体分区，若无此参数，则默认同步全部分区,partition值为system.part对应表的partition column -->
            <!-- 
              <enabled_partitions></enabled_partitions>
              -->
              <!--指定202111分区-->
              <enabled_partitions>
                        <partition>'202111'</partition>
              </enabled_partitions>
        </table_test_job>
    </tables>
</yandex>

将task.xml写入zk

在对应的zk集群节点，执行

./zkCli.sh -server localhost:12181 create /clickhouse/copier_task
./zkCli.sh -server localhost:12181 create /clickhouse/copier_task/task
# 创建任务信息
./zkCli.sh -server localhost:12181 create /clickhouse/copier_task/task/description "`cat task.xml`"
# 查看任务信息
./zkCli.sh -server localhost:12181 get /clickhouse/copier_task/task/description
# 更新任务信息
./zkCli.sh -server localhost:12181 set /clickhouse/copier_task/task/description "`cat task.xml`"

执行过程

在装有clickhouse-copier服务器自定义路径中运行
有疑问的可以clickhouse-copier --help
以下命令会根据读取zk集群配置 /clickhouse/copier_task/task/description所配置的task.xml，并将日志保存在当前目录下的logs中

启动任务

后台运行

clickhouse-copier --config zookeeper.xml --task-path /clickhouse/copier_task/task --base-dir ./logs &

日志分析

请添加图片描述

首先任务先要生成read_shard_n的文件路径，用于读取每个shard上的指定表的数据，任务日志如下：

2021.12.23 19:47:44.967318 [ 2676812 ] {} <Debug> ClusterCopier: Will copy 2 partitions from shard N2 (having a replica 172.16.0.122:9000, pull table ck_default.point_data_local of cluster src_manyun_ch_cluster
2021.12.23 19:50:24.851663 [ 2676811 ] {} <Debug> ClusterCopier: There are 2 destination partitions in shard N1 (having a replica 172.16.0.18:9000, pull table ck_default.point_data_local of cluster src_manyun_ch_cluster

然后是按照表的partition_key和orderby的所有字段的cityHash64取余10的结果作为条件将数据进行拆分，任务日志如下：

2021.12.23 19:50:24.855281 [ 2676811 ] {} <Debug> ClusterCopier: Checking shard N1 (having a replica 172.16.0.18:9000, pull table ck_default.point_data_local of cluster src_manyun_ch_cluster for partition 202110 piece 0 existence, executing query: SELECT 1 FROM _local.`.read_shard_0.des_manyun_ch_cluster.ck_default.point_data_test_local` WHERE (toYYYYMM(time) = (202110 AS partition_key)) AND (cityHash64(`device_guid`, `point_code`, `time`, `device_type`) % 10 = 0 ) LIMIT 1

注意：这里的split都是从%2Esplit%2Edes_manyun_ch_cluster%2Eck_default%2Epoint_data_test_local_piece中进行split的，并且是异步执行的，数据是流式的，没有数据直接落盘。
3. 对应这10个piece，在目的端会有10个表与之对应，表名为test_copy_piece_n（n为0,1,2,…,9），任务日志如下：

2021.12.23 19:50:43.641097 [ 2676807 ] {} <Debug> StorageDistributed (.read_shard_0.des_manyun_ch_cluster.ck_default.point_data_test_local): Auto-increment is 0
2021.12.23 19:50:43.641393 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local): Auto-increment is 0
2021.12.23 19:50:43.641728 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_0): Auto-increment is 0
2021.12.23 19:50:43.641986 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_1): Auto-increment is 0
2021.12.23 19:50:43.642230 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_2): Auto-increment is 0
2021.12.23 19:50:43.642467 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_3): Auto-increment is 0
2021.12.23 19:50:43.642702 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_4): Auto-increment is 0
2021.12.23 19:50:43.642936 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_5): Auto-increment is 0
2021.12.23 19:50:43.643168 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_6): Auto-increment is 0
2021.12.23 19:50:43.643398 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_7): Auto-increment is 0
2021.12.23 19:50:43.643619 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_8): Auto-increment is 0
2021.12.23 19:50:43.643857 [ 2676807 ] {} <Debug> StorageDistributed (.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_9): Auto-increment is 0
2021.12.23 19:50:43.648644 [ 2676807 ] {} <Debug> ClusterCopier: Processing /clickhouse/copier_task/task/tables/des_manyun_ch_cluster.ck_default.point_data_test_local/202112/piece_0/shards/1

并且可以通过下面日志可以看出，clickhouse_copier也是用的insert into … select的方式进行数据迁移的。


2021.12.23 19:50:45.481535 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_0` VALUES 
2021.12.23 20:01:08.933373 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_1` VALUES 
2021.12.23 20:11:34.144447 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_2` VALUES 
2021.12.23 20:22:05.581291 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_3` VALUES 
2021.12.23 20:32:42.431329 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_4` VALUES 
2021.12.23 20:43:09.202856 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_5` VALUES 
2021.12.23 20:53:40.903325 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_6` VALUES 
2021.12.23 21:04:11.449778 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_7` VALUES 
2021.12.23 21:14:42.446846 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_8` VALUES 
2021.12.23 21:25:12.636855 [ 2676807 ] {} <Debug> ClusterCopier: Executing INSERT query: INSERT INTO _local.`.split.des_manyun_ch_cluster.ck_default.point_data_test_local_piece_9` VALUES

在任务完成后，会将test_copy_piece_n表中的数据attach到test_copy中，任务日志如下：

2021.12.23 21:35:42.672750 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 0 to original table
2021.12.23 21:35:54.482164 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:35:54.482228 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 1 to original table
2021.12.23 21:36:06.144835 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:36:06.144906 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 2 to original table
2021.12.23 21:36:18.104823 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:36:18.104898 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 3 to original table
2021.12.23 21:36:30.188603 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:36:30.188673 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 4 to original table
2021.12.23 21:36:42.229121 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:36:42.229197 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 5 to original table
2021.12.23 21:36:55.973762 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:36:55.973846 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 6 to original table
2021.12.23 21:36:55.973902 [ 2676807 ] {} <Debug> ClusterCopier: Executing ALTER query:  ALTER TABLE ck_default.point_data_test_local ATTACH PARTITION 202109 FROM ck_default.point_data_test_local_piece_6
2021.12.23 21:37:12.261403 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:37:12.261475 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 7 to original table
2021.12.23 21:37:12.261500 [ 2676807 ] {} <Debug> ClusterCopier: Executing ALTER query:  ALTER TABLE ck_default.point_data_test_local ATTACH PARTITION 202109 FROM ck_default.point_data_test_local_piece_7
2021.12.23 21:37:27.623009 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:37:27.623069 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 8 to original table
2021.12.23 21:37:27.623087 [ 2676807 ] {} <Debug> ClusterCopier: Executing ALTER query:  ALTER TABLE ck_default.point_data_test_local ATTACH PARTITION 202109 FROM ck_default.point_data_test_local_piece_8
2021.12.23 21:37:40.992927 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:37:40.992987 [ 2676807 ] {} <Debug> ClusterCopier: Trying to move partition 202109 piece 9 to original table
2021.12.23 21:37:40.993029 [ 2676807 ] {} <Debug> ClusterCopier: Executing ALTER query:  ALTER TABLE ck_default.point_data_test_local ATTACH PARTITION 202109 FROM ck_default.point_data_test_local_piece_9
2021.12.23 21:37:55.531416 [ 2676807 ] {} <Information> ClusterCopier: Number of nodes that executed ALTER query successfully : 6
2021.12.23 21:37:55.536704 [ 2676807 ] {} <Information> ClusterCopier: It took 6297.173648588 seconds to copy partition 202109: 377.38 GB uncompressed bytes, 4.39 billion rows and 5356530 source blocks are copied

最后会将中间过程生成的test_copy_piece_n表都删除掉，任务日志如下：


2021.12.23 21:37:55.536783 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables
2021.12.23 21:37:55.536796 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 0
2021.12.23 21:37:55.536835 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_0
2021.12.23 21:37:55.538885 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.538944 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 1
2021.12.23 21:37:55.538961 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_1
2021.12.23 21:37:55.540567 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.540596 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 2
2021.12.23 21:37:55.540626 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_2
2021.12.23 21:37:55.542177 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.542206 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 3
2021.12.23 21:37:55.542220 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_3
2021.12.23 21:37:55.543788 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.543831 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 4
2021.12.23 21:37:55.543847 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_4
2021.12.23 21:37:55.545196 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.545225 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 5
2021.12.23 21:37:55.545253 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_5
2021.12.23 21:37:55.546966 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.546997 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 6
2021.12.23 21:37:55.547013 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_6
2021.12.23 21:37:55.548483 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.548532 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 7
2021.12.23 21:37:55.548549 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_7
2021.12.23 21:37:55.550149 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.550182 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 8
2021.12.23 21:37:55.550213 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_8
2021.12.23 21:37:55.551712 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.551741 [ 2676807 ] {} <Debug> ClusterCopier: Removing helping tables piece 9
2021.12.23 21:37:55.551769 [ 2676807 ] {} <Debug> ClusterCopier: Execute distributed DROP TABLE: DROP TABLE IF EXISTS ck_default.point_data_test_local_piece_9
2021.12.23 21:37:55.581328 [ 2676807 ] {} <Information> ClusterCopier: DROP TABLE query was successfully executed on 6 nodes.
2021.12.23 21:37:55.581638 [ 2676807 ] {} <Debug> MemoryTracker: Peak memory usage (for query): 2.25 GiB.
2021.12.23 21:37:55.581696 [ 2676807 ] {} <Debug> MemoryTracker: Peak memory usage (for query): 2.25 GiB.

至此，迁移任务执行完毕。

补充说明

clickhouse_copier为了能保证任务失败可以继续执行，会在zk上保留一些状态信息。
在zk上除了刚刚自行创建的description，还自动生成了其余三个。tables记录了表的同步任务，如下：如task.xml所配置的相同

[zk: localhost:12181(CONNECTED) 7] ls /clickhouse/copier_task/task/tables 
[des_manyun_ch_cluster.ck_default.point_data_test_local]

task_active_workers记录了有哪些正在执行任务的worker

[zk: localhost:12181(CONNECTED) 7] ls /clickhouse/copier_task/task/task_active_workers
des_manyun_ch_cluster.ck_default.point_data_test_local_copy

task_active_workers_version记录了任务执行到哪个阶段，如下：

[zk: localhost:12181(CONNECTED) 11] get /clickhouse/copier_task/task/task_active_workers_version
/clickhouse/copier_task/task/tables/des_manyun_ch_cluster.ck_default.point_data_test_local/202109/piece_9/shards/2