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188 lines
7.7 KiB
Markdown
188 lines
7.7 KiB
Markdown
---
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slug: /en/operations/utilities/clickhouse-copier
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sidebar_position: 59
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sidebar_label: clickhouse-copier
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---
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# clickhouse-copier
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Copies data from the tables in one cluster to tables in another (or the same) cluster.
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:::warning
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To get a consistent copy, the data in the source tables and partitions should not change during the entire process.
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:::
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You can run multiple `clickhouse-copier` instances on different servers to perform the same job. ClickHouse Keeper, or ZooKeeper, is used for syncing the processes.
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After starting, `clickhouse-copier`:
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- Connects to ClickHouse Keeper and receives:
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- Copying jobs.
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- The state of the copying jobs.
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- It performs the jobs.
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Each running process chooses the “closest” shard of the source cluster and copies the data into the destination cluster, resharding the data if necessary.
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`clickhouse-copier` tracks the changes in ClickHouse Keeper and applies them on the fly.
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To reduce network traffic, we recommend running `clickhouse-copier` on the same server where the source data is located.
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## Running Clickhouse-copier {#running-clickhouse-copier}
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The utility should be run manually:
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``` bash
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$ clickhouse-copier --daemon --config keeper.xml --task-path /task/path --base-dir /path/to/dir
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```
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Parameters:
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- `daemon` — Starts `clickhouse-copier` in daemon mode.
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- `config` — The path to the `keeper.xml` file with the parameters for the connection to ClickHouse Keeper.
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- `task-path` — The path to the ClickHouse Keeper node. This node is used for syncing `clickhouse-copier` processes and storing tasks. Tasks are stored in `$task-path/description`.
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- `task-file` — Optional path to file with task configuration for initial upload to ClickHouse Keeper.
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- `task-upload-force` — Force upload `task-file` even if node already exists.
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- `base-dir` — The path to logs and auxiliary files. When it starts, `clickhouse-copier` creates `clickhouse-copier_YYYYMMHHSS_<PID>` subdirectories in `$base-dir`. If this parameter is omitted, the directories are created in the directory where `clickhouse-copier` was launched.
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## Format of keeper.xml {#format-of-zookeeper-xml}
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``` xml
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<clickhouse>
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<logger>
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<level>trace</level>
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<size>100M</size>
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<count>3</count>
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</logger>
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<zookeeper>
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<node index="1">
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<host>127.0.0.1</host>
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<port>2181</port>
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</node>
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</zookeeper>
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</clickhouse>
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```
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## Configuration of Copying Tasks {#configuration-of-copying-tasks}
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``` xml
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<clickhouse>
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<!-- Configuration of clusters as in an ordinary server config -->
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<remote_servers>
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<source_cluster>
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<!--
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source cluster & destination clusters accept exactly the same
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parameters as parameters for the usual Distributed table
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see https://clickhouse.com/docs/en/engines/table-engines/special/distributed/
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-->
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<shard>
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<internal_replication>false</internal_replication>
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<replica>
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<host>127.0.0.1</host>
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<port>9000</port>
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<!--
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<user>default</user>
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<password>default</password>
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<secure>1</secure>
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-->
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</replica>
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</shard>
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...
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</source_cluster>
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<destination_cluster>
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...
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</destination_cluster>
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</remote_servers>
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<!-- How many simultaneously active workers are possible. If you run more workers superfluous workers will sleep. -->
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<max_workers>2</max_workers>
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<!-- Setting used to fetch (pull) data from source cluster tables -->
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<settings_pull>
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<readonly>1</readonly>
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</settings_pull>
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<!-- Setting used to insert (push) data to destination cluster tables -->
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<settings_push>
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<readonly>0</readonly>
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</settings_push>
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<!-- Common setting for fetch (pull) and insert (push) operations. Also, copier process context uses it.
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They are overlaid by <settings_pull/> and <settings_push/> respectively. -->
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<settings>
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<connect_timeout>3</connect_timeout>
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<!-- Sync insert is set forcibly, leave it here just in case. -->
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<insert_distributed_sync>1</insert_distributed_sync>
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</settings>
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<!-- Copying tasks description.
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You could specify several table task in the same task description (in the same ZooKeeper node), they will be performed
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sequentially.
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-->
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<tables>
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<!-- A table task, copies one table. -->
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<table_hits>
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<!-- Source cluster name (from <remote_servers/> section) and tables in it that should be copied -->
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<cluster_pull>source_cluster</cluster_pull>
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<database_pull>test</database_pull>
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<table_pull>hits</table_pull>
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<!-- Destination cluster name and tables in which the data should be inserted -->
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<cluster_push>destination_cluster</cluster_push>
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<database_push>test</database_push>
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<table_push>hits2</table_push>
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<!-- Engine of destination tables.
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If destination tables have not be created, workers create them using columns definition from source tables and engine
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definition from here.
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NOTE: If the first worker starts insert data and detects that destination partition is not empty then the partition will
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be dropped and refilled, take it into account if you already have some data in destination tables. You could directly
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specify partitions that should be copied in <enabled_partitions/>, they should be in quoted format like partition column of
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system.parts table.
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-->
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<engine>
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ENGINE=ReplicatedMergeTree('/clickhouse/tables/{cluster}/{shard}/hits2', '{replica}')
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PARTITION BY toMonday(date)
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ORDER BY (CounterID, EventDate)
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</engine>
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<!-- Sharding key used to insert data to destination cluster -->
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<sharding_key>jumpConsistentHash(intHash64(UserID), 2)</sharding_key>
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<!-- Optional expression that filter data while pull them from source servers -->
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<where_condition>CounterID != 0</where_condition>
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<!-- This section specifies partitions that should be copied, other partition will be ignored.
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Partition names should have the same format as
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partition column of system.parts table (i.e. a quoted text).
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Since partition key of source and destination cluster could be different,
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these partition names specify destination partitions.
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NOTE: In spite of this section is optional (if it is not specified, all partitions will be copied),
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it is strictly recommended to specify them explicitly.
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If you already have some ready partitions on destination cluster they
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will be removed at the start of the copying since they will be interpeted
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as unfinished data from the previous copying!!!
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-->
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<enabled_partitions>
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<partition>'2018-02-26'</partition>
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<partition>'2018-03-05'</partition>
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...
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</enabled_partitions>
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</table_hits>
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<!-- Next table to copy. It is not copied until previous table is copying. -->
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<table_visits>
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...
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</table_visits>
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...
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</tables>
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</clickhouse>
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```
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`clickhouse-copier` tracks the changes in `/task/path/description` and applies them on the fly. For instance, if you change the value of `max_workers`, the number of processes running tasks will also change.
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