Migrate data from an ApsaraDB RDS for MySQL instance to a Tablestore instance - Data Transmission Service

This topic describes how to migrate data from an ApsaraDB RDS for MySQL instance to a Tablestore instance by using Data Transmission Service (DTS).

Supported source databases

You can use DTS to migrate data from the following types of MySQL databases to a Tablestore instance:

ApsaraDB RDS for MySQL
Self-managed MySQL databases:
- Self-managed database with a public IP address
- Self-managed database that is hosted on an Elastic Compute Service (ECS) instance
- Self-managed database that is connected over Database Gateway
- Self-managed database connected over Cloud Enterprise Network (CEN)
- Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway

Note

In this topic, an ApsaraDB RDS for MySQL instance is used to describe how to configure a data migration task. You can also follow the procedure to configure data migration tasks for other types of MySQL databases.

Prerequisites

An ApsaraDB RDS for MySQL instance is created. For more information, see Create an ApsaraDB RDS for MySQL instance.
A Tablestore instance is created. For more information, see Use Tablestore.
The available storage space of the destination Tablestore instance is larger than the total size of data in the source ApsaraDB RDS for MySQL instance.

Limits

Category	Description
Limits on the source database	The tables to be migrated must have PRIMARY KEY or UNIQUE constraints, and all fields must be unique. Otherwise, the destination database may contain duplicate data records. If you select tables as the objects to be migrated and you need to edit tables, such as renaming tables or columns, in the destination database, up to 1,000 tables can be migrated in a single data migration task. If you run a task to migrate more than 1,000 tables, a request error occurs. In this case, we recommend that you configure multiple tasks to migrate the tables in batches or configure a task to migrate the entire database. The binary logging feature must be enabled for the ApsaraDB RDS for MySQL instance. The binlog_format parameter must be set to row, and the binlog_row_image parameter must be set to full. For more information, see Modify instance parameters. Otherwise, error messages are returned during precheck and the data migration task cannot be started. During schema migration and full data migration, do not perform DDL operations to change the schemas of databases or tables. Otherwise, the data migration task fails. If you do not select incremental data migration as a migration type, make sure that no data is written to the source database during data migration. Otherwise, data inconsistency may occur between the source and destination databases. To ensure data consistency, we recommend that you select schema migration, full data migration, and incremental data migration as the migration types.
Other limits	We recommend that you do not use tools such as pt-online-schema-change to perform DDL operations on objects during data migration. Otherwise, data migration may fail. DTS uses the `ROUND(COLUMN,PRECISION)` function to retrieve values from columns of the FLOAT or DOUBLE data type. If you do not specify a precision, DTS sets the precision for the FLOAT data type to 38 digits and the precision for the DOUBLE data type to 308 digits. You must check whether the precision settings meet your business requirements. Before you migrate data, evaluate the impact of data migration on the performance of the source and destination databases. We recommend that you migrate data during off-peak hours. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads on the database servers. During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the size of used tablespace of the destination database is larger than that of the source instance. DTS attempts to resume data migration tasks that failed within the last seven days. Before you switch workloads to the destination database, stop or release the data migration task. You can also execute the `REVOKE` statement to revoke the write permissions from the account used by DTS to access the destination database. Otherwise, the data in the source database overwrites the data in the destination database after a failed task is resumed. You can migrate at most 64 tables to the Tablestore instance. If you want to migrate more than 64 tables to the Tablestore instance, you can disable the limit for the destination Tablestore instance. The names of the tables and columns to be migrated must comply with the naming conventions of the Tablestore instance. The name of a table or a column can contain letters, digits, and underscores (_). The name must start with a letter or underscore (_). The name of a table or a column must be 1 to 255 characters in length.

Billing

Migration type	Task configuration fee	Internet traffic fee
Schema migration and full data migration	Free of charge	Charged only when data is migrated from Alibaba Cloud over the Internet. For more information, see Billing overview.
Incremental data migration	Charged. For more information, see Billing overview.

Migration types

Schema migration
DTS migrates the schemas of required objects from the source database to the destination database.
Full data migration
DTS migrates the historical data of objects from the source database to the destination database.
Incremental data migration
After full data migration is complete, DTS migrates incremental data from the source database to the destination database. Incremental data migration ensures service continuity of self-managed applications during data migration.

SQL operations that can be migrated during incremental data migration

Operation type	SQL statement
DML	INSERT, UPDATE, and DELETE

Permissions required for database accounts

Database	Schema migration	Full data migration	Incremental data migration
ApsaraDB RDS for MySQL	The SELECT permission	The SELECT permission	The SELECT permission on the objects to be migrated, the REPLICATION SLAVE permission and the REPLICATION CLIENT permission. DTS automatically grants these permissions to the database account.

For more information about how to create a database account and grant permissions to the database account of an ApsaraDB RDS for MySQL instance, see Create an account on an ApsaraDB RDS for MySQL instance and Modify the permissions of a standard account on an ApsaraDB RDS for MySQL instance.

Procedure

Go to the Data Migration Tasks page.
1. Log on to the Data Management (DMS) console.
2. In the top navigation bar, click DTS.
3. In the left-side navigation pane, choose DTS (DTS) > Data Migration.
Note
- Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Customize the layout and style of the DMS console.
- You can also go to the Data Migration Tasks page of the new DTS console.
From the drop-down list next to Data Migration Tasks, select the region in which your data migration instance resides.
Note
If you use the new DTS console, select the region in which the data migration instance resides in the top navigation bar.

Click Create Task. In the Create Task wizard, configure the source and destination databases.

Section	Parameter	Description
N/A	Task Name	The name of the task. DTS automatically assigns a name to the task. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
Source Database	Select an existing DMS database instance	The database instance that you want to use. You can determine whether to select an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the instance. If you do not select an existing instance, you must configure parameters for the destination database.
	Database Type	The type of the source database. Select MySQL.
	Access Method	The access method of the source database. Select Alibaba Cloud Instance.
	Instance Region	The region in which the source ApsaraDB RDS for MySQL instance resides.
	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to migrate data across Alibaba Cloud accounts. In this example, No is selected.
	RDS Instance ID	The ID of the source ApsaraDB RDS for MySQL instance.
	Database Account	The database account of the source ApsaraDB RDS for MySQL instance. For more information about the permissions that are required for the account, see the Permissions required for database accounts section of this topic.
	Database Password	The password of the database account.
	Encryption	Specifies whether to encrypt the connection to the source database. You can select Non-encrypted or SSL-encrypted based on your business requirements. If you select SSL-encrypted, you must enable SSL encryption for the ApsaraDB RDS for MySQL instance before you configure the data migration task. For more information, see Configure the SSL encryption feature.
Destination Database	Select an existing DMS database instance	The database instance that you want to use. You can choose whether to select an existing instance based on your business requirements. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
	Database Type	The type of the destination database. Select Tablestore.
	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
	Instance Region	The region in which the destination Tablestore instance resides.
	Instance ID	The ID of the destination Tablestore instance.
	AccessKey ID of Alibaba Cloud Account	The AccessKey ID of the account that you use to connect to the destination Tablestore instance. For more information, see Create an AccessKey pair.
	AccessKey Secret of Alibaba Cloud Account	The AccessKey secret of the account that you use to connect to the destination Tablestore instance. For more information, see Create an AccessKey pair.

In the lower part of the page, click Test Connectivity and Proceed.
If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the IP address whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must make sure that the ECS instance can access the database. If the self-managed database is hosted on multiple ECS instances, you must manually add the CIDR blocks of DTS servers to the security group rules of each ECS instance. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the IP address whitelist of the database to allow DTS to access the database. For more information, see the "CIDR blocks of DTS servers" section of the Add the CIDR blocks of DTS servers to the security settings of on-premises databases topic.
Warning
If the public CIDR blocks of DTS servers are automatically or manually added to the IP address whitelist of a database instance or to the security group rules of an ECS instance, security risks may arise. Therefore, before you use DTS to migrate data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your account and password, limiting the ports that are exposed, authenticating API calls, regularly checking the IP address whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, and connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

Configure the objects to be migrated and advanced settings.

Parameter	Description
Migration Types	To perform only full data migration, select Schema Migration and Full Data Migration. To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that have the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started. Note You can use the object name mapping feature to rename the tables that are migrated to the destination database. You can use this feature if the source and destination databases contain tables that have identical table names and the tables in the destination database cannot be deleted or renamed. For more information, see Map object names. Ignore Errors and Proceed: skips the precheck for identical table names in the source and destination databases. Warning If you select Ignore Errors and Proceed, data inconsistency may occur and your business may be exposed to the following potential risks: If the source and destination databases have the same schema, DTS does not migrate data records that have the same primary keys as data records in the destination database. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails.
Operation Types	Select the types of operations that you want to migrate based on your business requirements. By default, all operation types are selected.
Processing Policy of Dirty Data	The processing policy for handling data write errors. Valid values: Skip Block
Data Write Mode	The mode in which data is written. Valid values: Update Row: The PutRowChange operation is performed to update rows in the Tablestore instance. Overwrite Row: The UpdateRowChange operation is performed to overwrite rows in the Tablestore instance.
Batch Write Mode	The operation that is used to write multiple rows of data to the Tablestore instance at a time. Valid values: BulkImportRequest: Data is written offline. BatchWriteRowRequest: Multiple rows of data are written at a time. To achieve higher read and write efficiency and reduce your costs of using the Tablestore instance, we recommend that you select BulkImportRequest.
More	You can configure the following parameters based on your business requirements: Queue Size: the length of the queue for writing data to the Tablestore instance. Thread Quantity: the number of callback threads for writing data to the Tablestore instance. Concurrency: the maximum number of concurrent threads for the Tablestore instance. Buckets: the number of concurrent buckets for writing incremental data in sequence. To improve the concurrent write capability, you can set this parameter to a large value. Note The value must be less than or equal to the maximum number of concurrent threads.
Capitalization of Object Names in Destination Instance	The capitalization of database names, table names, and column names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that in the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Source Objects	Select one or more objects from the Source Objects section. Click the icon and add the objects to the Selected Objects section. Note You can select tables or databases as the objects to be migrated. If you select tables as the objects to be migrated, DTS does not migrate other objects such as views, triggers, and stored procedures to the destination database. If you select Tablestore as the destination database type, you can migrate tables only in a single database. You can select only one database or multiple tables in the same database.
Selected Objects	To rename an object that you want to migrate to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object. To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time. Note Only table name mapping is supported. If you use the object name mapping feature to rename an object, other objects that are dependent on the object may fail to be migrated. To specify WHERE conditions to filter data, right-click a table in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Use SQL conditions to filter data.

Optional: In the Selected Objects section, move the pointer over a table, and then click Edit. In the dialog box that appears, configure the data type of each column in the Tablestore instance.

Click Next: Advanced Settings to configure advanced settings.

Parameter	Description
Set Alerts	Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts will receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. If you select Yes, you must also specify the alert threshold and alert contacts. For more information, see Configure monitoring and alerting.
Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data migration task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you set different retry time ranges for multiple data migration tasks that have the same source or destination database, the shortest retry time range that is set takes precedence. When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
Configure ETL	Specifies whether to configure the extract, transform, and load (ETL) feature. For more information, see What is ETL?. Valid values: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.

Click Next: Configure Database and Table Fields to configure the primary key columns of the tables that you want to migrate to the Tablestore instance.
In the lower part of the page, click Next: Save Task Settings and Precheck.
You can move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters to view the parameters to be specified when you call the relevant API operation to configure the DTS task.
Note
- Before you can start the data migration task, DTS performs a precheck. You can start the data migration task only after the task passes the precheck.
- If the task fails to pass the precheck, click View Details next to each failed item. After you troubleshoot the issues based on the error message, you can run a precheck again.
- If an alert is triggered for an item during the precheck:
  If the alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issues. Then, run a precheck again.
  If the alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.
Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

Section	Parameter	Description
New Instance Class	Resource Group	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
New Instance Class	Instance Class	DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Specifications of data migration instances.

Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.
Click Buy and Start to start the data migration task. You can view the progress of the task in the task list.