Version: Stable-3.1

Cross-cluster Data Migration Tool

The StarRocks Cross-cluster Data Migration Tool is provided by StarRocks Community. You can use this tool to easily migrate data from the source cluster to the target cluster.

note

The StarRocks Cross-cluster Data Migration Tool only supports migrating data from a shared-nothing cluster to either another shared-nothing cluster or a shared-data cluster.
The StarRocks version of the target cluster must be v3.1.8, v3.2.3, or later.

Preparations

The following preparations must be performed on the target cluster for data migration.

Enable Legacy Compatibility for Replication

StarRocks may behave differently between the old and new versions, causing problems during cross-cluster data migration. Therefore, you must enable Legacy Compatibility for the target cluster before data migration and disable it after data migration is completed.

You can check whether Legacy Compatibility for Replication is enabled by using the following statement:
```
ADMIN SHOW FRONTEND CONFIG LIKE 'enable_legacy_compatibility_for_replication';
```
If true is returned, it indicates that Legacy Compatibility for Replication is enabled.

Dynamically enable Legacy Compatibility for Replication:

ADMIN SET FRONTEND CONFIG("enable_legacy_compatibility_for_replication"="true");

To prevent Legacy Compatibility for Replication from automatically disabling during the data migration process in case of cluster restart, you also need to add the following configuration item in the FE configuration file fe.conf:
```
enable_legacy_compatibility_for_replication = true
```

After the data migration is completed, you need to remove the configuration enable_legacy_compatibility_for_replication = true from the configuration file, and dynamically disable Legacy Compatibility for Replication using the following statement:

ADMIN SET FRONTEND CONFIG("enable_legacy_compatibility_for_replication"="false");

Disable Compaction

If the target cluster for data migration is a shared-data cluster, you need to manually disable Compaction before starting the data migration and re-enable it after the data migration is completed.

You can check whether Compaction is enabled by using the following statement:
```
ADMIN SHOW FRONTEND CONFIG LIKE 'lake_compaction_max_tasks';
```
If 0 is returned, it indicates that Compaction is disabled.

Dynamically disable Compaction:

ADMIN SET FRONTEND CONFIG("lake_compaction_max_tasks"="0");

To prevent Compaction from automatically enabling during the data migration process in case of cluster restart, you also need to add the following configuration item in the FE configuration file fe.conf:
```
lake_compaction_max_tasks = 0
```

After the data migration is completed, you need to remove the configuration lake_compaction_max_tasks = 0 from the configuration file, and dynamically enable Compaction using the following statement:

ADMIN SET FRONTEND CONFIG("lake_compaction_max_tasks"="-1");

Disable column filtering

The optimization for unused column filtering at the Scan stage may cause a crash during queries against the migrated data. You need to disable this optimization before data migration:

SET GLOBAL enable_filter_unused_columns_in_scan_stage=false;

enable_filter_unused_columns_in_scan_stage

Description: Whether to filter unused column at the Scan stage.
Default: true
Introduced in: v3.1

Configure Data Migration (Optional)

You can configure data migration operations using the following FE and BE parameters. In most cases, the default configuration can meet your needs. If you wish to use the default configuration, you can skip this step.

note

Please note that increasing the values of the following configuration items can accelerate migration but will also increase the load pressure on the source cluster.

FE Parameters

The following FE parameters are dynamic configuration items. Refer to Configure FE Dynamic Parameters on how to modify them.

Parameter	Default	Unit	Description
replication_max_parallel_table_count	100	-	The maximum number of concurrent data synchronization tasks allowed. StarRocks creates one synchronization task for each table.
replication_max_parallel_replica_count	10240	-	The maximum number of tablet replica allowed for concurrent synchronization.
replication_max_parallel_data_size_mb	1048576	MB	The maximum size of data allowed for concurrent synchronization.
replication_transaction_timeout_sec	86400	Seconds	The timeout duration for synchronization tasks.

BE Parameters

The following BE parameter is a dynamic configuration item. Refer to Configure BE Dynamic Parameters on how to modify it.

Parameter	Default	Unit	Description
replication_threads	0	-	The number of threads for executing synchronization tasks. `0` indicates setting the number of threads to the 4 times of number of CPU cores on the machine where the BE resides.

Step 1: Install the Tool

It is recommended to install the migration tool on the server where the target cluster resides.

Launch a terminal, and download the binary package of the tool.

wget https://releases.starrocks.io/starrocks/starrocks-cluster-sync.tar.gz

Decompress the package.
```
tar -xvzf starrocks-cluster-sync.tar.gz
```

Step 2: Configure the Tool

Navigate to the extracted folder and modify the configuration file conf/sync.properties.

cd starrocks-cluster-sync
vi conf/sync.properties

The file content is as follows:

# If true, all tables will be synchronized only once, and the program will exit automatically after completion.
one_time_run_mode=false

source_fe_host=
source_fe_query_port=9030
source_cluster_user=root
source_cluster_password=
source_cluster_password_secret_key=
source_cluster_token=

target_fe_host=
target_fe_query_port=9030
target_cluster_user=root
target_cluster_password=
target_cluster_password_secret_key=

# Comma-separated list of database names or table names like <db_name> or <db_name.table_name>
# example: db1,db2.tbl2,db3
# Effective order: 1. include 2. exclude
include_data_list=
exclude_data_list=

# If there are no special requirements, please maintain the default values for the following configurations.
target_cluster_storage_volume=
target_cluster_replication_num=-1
target_cluster_max_disk_used_percent=80

max_replication_data_size_per_job_in_gb=-1

meta_job_interval_seconds=180
meta_job_threads=4
ddl_job_interval_seconds=10
ddl_job_batch_size=10
ddl_job_allow_drop_target_only=false
ddl_job_allow_drop_schema_change_table=true
ddl_job_allow_drop_inconsistent_partition=true
ddl_job_allow_drop_partition_target_only=true
replication_job_interval_seconds=10
replication_job_batch_size=10
report_interval_seconds=300

The description of the parameters is as follows:

Parameter	Description
one_time_run_mode	Whether to enable one-time synchronization mode. When one-time synchronization mode is enabled, the migration tool only performs full synchronization instead of incremental synchronization.
source_fe_host	The IP address or FQDN (Fully Qualified Domain Name) of the source cluster's FE.
source_fe_query_port	The query port (`query_port`) of the source cluster's FE.
source_cluster_user	The username used to log in to the source cluster. This user must be granted the OPERATE privilege on the SYSTEM level.
source_cluster_password	The user password used to log in to the source cluster.
source_cluster_password_secret_key	The secret key used to encrypt the password of the login user for the source cluster. The default value is an empty string, which means that the login password is not encrypted. If you want to encrypt `source_cluster_password`, you can get the encrypted `source_cluster_password` string by using SQL statement `SELECT TO_BASE64(AES_ENCRYPT('<source_cluster_password>','<source_cluster_password_ secret_key>'))`.
source_cluster_token	Token of the source cluster. For information on how to obtain the cluster token, refer to Obtain Cluster Token below.
target_fe_host	The IP address or FQDN (Fully Qualified Domain Name) of the target cluster's FE.
target_fe_query_port	The query port (`query_port`) of the target cluster's FE.
target_cluster_user	The username used to log in to the target cluster. This user must be granted the OPERATE privilege on the SYSTEM level.
target_cluster_password	The user password used to log in to the target cluster.
target_cluster_password_secret_key	The secret key used to encrypt the password of the login user for the target cluster. The default value is an empty string, which means that the login password is not encrypted. If you want to encrypt `target_cluster_password`, you can get the encrypted `target_cluster_password` string by using SQL statement `SELECT TO_BASE64(AES_ENCRYPT('<target_cluster_password>','<target_cluster_password_ secret_key>'))`.
include_data_list	The databases and tables that need to be migrated, with multiple objects separated by commas (`,`). For example: `db1, db2.tbl2, db3`. This item takes effect prior to `exclude_data_list`. If you want to migrate all databases and tables in the cluster, you do not need to configure this item.
exclude_data_list	The databases and tables that do not need to be migrated, with multiple objects separated by commas (`,`). For example: `db1, db2.tbl2, db3`. `include_data_list` takes effect prior to this item. If you want to migrate all databases and tables in the cluster, you do not need to configure this item.
target_cluster_storage_volume	The storage volume used to store tables in the target cluster when the target cluster is a shared-data cluster. If you want to use the default storage volume, you do not need to specify this item.
target_cluster_replication_num	The number of replicas specified when creating tables in the target cluster. If you want to use the same replica number as the source cluster, you do not need to specify this item.
target_cluster_max_disk_used_percent	Disk usage percentage threshold for BE nodes of the target cluster when the target cluster is shared-nothing. Migration is terminated when the disk usage of any BE in the target cluster exceeds this threshold. The default value is `80`, which means 80%.
meta_job_interval_seconds	The interval, in seconds, at which the migration tool retrieves metadata from the source and target clusters. You can use the default value for this item.
meta_job_threads	The number of threads used by the migration tool to obtain metadata from the source and target clusters. You can use the default value for this item.
ddl_job_interval_seconds	The interval, in seconds, at which the migration tool executes DDL statements on the target cluster. You can use the default value for this item.
ddl_job_batch_size	The batch size for executing DDL statements on the target cluster. You can use the default value for this item.
ddl_job_allow_drop_target_only	Whether to allow the migration tool to delete databases or tables that exist only in the target cluster but not in the source cluster. The default is `false`, which means they will not be deleted. You can use the default value for this item.
ddl_job_allow_drop_schema_change_table	Whether to allow the migration tool to delete tables with inconsistent schemas between the source and target clusters. The default is `true`, meaning they will be deleted. You can use the default value for this item. The migration tool will automatically synchronize the deleted tables during the migration.
ddl_job_allow_drop_inconsistent_partition	Whether to allow the migration tool to delete partitions with inconsistent data distribution between the source and target clusters. The default is `true`, meaning they will be deleted. You can use the default value for this item. The migration tool will automatically synchronize the deleted partitions during the migration.
ddl_job_allow_drop_partition_target_only	Whether to allow the migration tool to delete partitions that are deleted in the source cluster to keep the partitions consistent between the source and target clusters. The default is `true`, meaning they will be deleted. You can use the default value for this item.
replication_job_interval_seconds	The interval, in seconds, at which the migration tool triggers data synchronization tasks. You can use the default value for this item.
replication_job_batch_size	The batch size at which the migration tool triggers data synchronization tasks. You can use the default value for this item.
max_replication_data_size_per_job_in_gb	The data size threshold at which the migration tool triggers data synchronization tasks. Unit: GB. Multiple data synchronization tasks will be triggered if the size of the partition to be migrated exceed this value. The default value is `-1`, meaning no limit is imposed, and all partitions in a table will be migrated in a single synchronization task. You can set this parameter to restrict the data size of each task if the table to be migrated has a large data volume.
report_interval_seconds	The time interval at which the migration tool prints the progress information. Unit: Seconds. Default value: `300`. You can use the default value for this item.

Obtain Cluster Token

The Cluster Token is available in the FE metdata. Log in to the server where the FE node is located and run the following command:

cat fe/meta/image/VERSION | grep token

Output:

token=wwwwwwww-xxxx-yyyy-zzzz-uuuuuuuuuu

During data migration, the migration tool needs to access all FE nodes of both the source and target clusters, and the target cluster needs to access all BE and CN nodes of the source cluster.

You can obtain the network addresses of these nodes by executing the following statements on the corresponding cluster:

-- Obtain the network addresses of FE nodes in a cluster.
SHOW FRONTENDS;
-- Obtain the network addresses of BE nodes in a cluster.
SHOW BACKENDS;
-- Obtain the network addresses of CN nodes in a cluster.
SHOW COMPUTE NODES;

If these nodes use private addresses that cannot be accessed outside the cluster, such as internal network addresses within a Kubernetes cluster, you need to map these private addresses to addresses that can be accessed from outside.

Navigate to the extracted folder of the tool and modify the configuration file conf/hosts.properties。

cd starrocks-cluster-sync
vi conf/hosts.properties

The default content of the file is as follows, describing how network address mapping is configured:

# <SOURCE/TARGET>_<domain>=<IP>

The following example performs these operations:

Map the source cluster's private network addresses 192.1.1.1 and 192.1.1.2 to 10.1.1.1 and 10.1.1.2.
Map the target cluster's private network address fe-0.starrocks.svc.cluster.local to 10.1.2.1.

# <SOURCE/TARGET>_<domain>=<IP>
SOURCE_192.1.1.1=10.1.1.1
SOURCE_192.1.1.2=10.1.1.2
TARGET_fe-0.starrocks.svc.cluster.local=10.1.2.1

Step 3: Start the Migration Tool

After configuring the tool, start the migration tool to initiate the data migration process.

./bin/start.sh

note

Make sure that the BE nodes of the source and target clusters can properly communicate via the network.
During runtime, the migration tool regularly checks whether the data in the target cluster is lagging behind the source cluster. If there is a lag, it initiates data migration tasks.
If new data is constantly loaded into the source cluster, data synchronization will continue until the data in the target cluster is consistent with that in the source cluster.
You can query tables in the target cluster during migration, but do not load new data into the tables, as it may result in inconsistencies between the data in the target cluster and the source cluster. Currently, the migration tool does not forbid data loading into the target cluster during migration.
Note that data migration does not automatically terminate. You need to manually check and confirm the completion of migration and then stop the migration tool.

View Migration Progress

View Migration Tool logs

You can check the migration progress through the migration tool log log/sync.INFO.log.

Example 1: View task progress.

The important metrics are as follows:

Sync job progress: The progress of data migration. The migration tool regularly checks whether the data in the target cluster is lagging behind the source cluster. Therefore, a progress of 100% only means that the data synchronization is completed within the current check interval. If new data continues to be loaded into the source cluster, the progress may decrease in the next check interval.
total: The total number of all types of jobs in this migration operation.
ddlPending: The number of DDL jobs pending to be executed.
jobPending: The number of pending data synchronization jobs to be executed.
sent: The number of data synchronization jobs sent from the source cluster but not yet started. Theoretically, this value should not be too large. If the value keeps increasing, please contact our engineers.
running: The number of data synchronization jobs that are currently running.
finished: The number of data synchronization jobs that are finished.
failed: The number of failed data synchronization jobs. Failed data synchronization jobs will be resent. Therefore, in most cases, you can ignore this metric. If this value is significantly large, please contact our engineers.
unknown: The number of jobs with an unknown status. Theoretically, this value should always be 0. If this value is not 0, please contact our engineers.

Example 2: View the table migration progress.

Sync table progress: Table migration progress, that is, the ratio of tables that have been migrated in this migration task to all the tables that need to be migrated.
finishedTableRatio: Ratio of tables with at least one successful synchronization task execution.
expiredTableRatio: Ratio of tables with expired data.
total table: Total number of tables involved in this data migration progress.
finished table: Number of tables with at least one successful synchronization task execution.
unfinished table: Number of tables with no synchronization task execution.
expired table: Number of tables with expired data.

View Migration Transaction Status

The migration tool opens a transaction for each table. You can view the status of the migration for a table by checking the status of its corresponding transaction.

SHOW PROC "/transactions/<db_name>/running";

<db_name> is the name of the database where the table is located.

View Partition Data Versions

You can compare the data versions of the corresponding partitions in the source and target clusters to view the migration status of that partition.

SHOW PARTITIONS FROM <table_name>;

<table_name> is the name of the table to which the partition belongs.

View Data Volume

You can compare the data volumes in the source and target clusters to view the migration status.

SHOW DATA;

View Table Row Count

You can compare the row counts of tables in the source and target clusters to view the migration status of each table.

SELECT 
  TABLE_NAME, 
  TABLE_ROWS 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_TYPE = 'BASE TABLE' 
ORDER BY TABLE_NAME;

Limits

The list of objects that support synchronization currently is as follows (those not included indicate that synchronization is not supported):

Databases
Internal tables and their data
Materialized view schemas and their building statements (The data in the materialized view will not be synchronized. And if the base tables of the materialized view is not synchronized to the target cluster, the background refresh task of the materialized view reports an error.)
Logical views

Q&A

Q1: Which ports need to be opened between clusters?

If you have enabled the firewall, you must open these ports:

Component	Port	Default
FE	query_port	9030
FE	http_port	8030
FE	rpc_port	9020
BE	be_http_port	8040
BE	be_port	9060

Cross-cluster Data Migration Tool

Preparations​

Enable Legacy Compatibility for Replication​

Disable Compaction​

Disable column filtering​

enable_filter_unused_columns_in_scan_stage​

Configure Data Migration (Optional)​

FE Parameters​

BE Parameters​

Step 1: Install the Tool​

Step 2: Configure the Tool​

Migration-related configuration​

Obtain Cluster Token​

Network-related configuration (Optional)​

Step 3: Start the Migration Tool​

View Migration Progress​

View Migration Tool logs​

View Migration Transaction Status​

View Partition Data Versions​

View Data Volume​

View Table Row Count​

Limits​

Q&A​

Q1: Which ports need to be opened between clusters?​

What did you think of this doc?

Preparations

Enable Legacy Compatibility for Replication

Disable Compaction

Disable column filtering

enable_filter_unused_columns_in_scan_stage

Configure Data Migration (Optional)

FE Parameters

BE Parameters

Step 1: Install the Tool

Step 2: Configure the Tool

Migration-related configuration

Obtain Cluster Token

Network-related configuration (Optional)

Step 3: Start the Migration Tool

View Migration Progress

View Migration Tool logs

View Migration Transaction Status

View Partition Data Versions

View Data Volume

View Table Row Count

Limits

Q&A

Q1: Which ports need to be opened between clusters?