This topic describes how to migrate data from a MaxCompute project to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS).
- DTS uses read and write resources of the source and destination databases during full data migration. This may increase the loads of the database servers. If the database performance is unfavorable, the specification is low, or the data volume is large, database services may become unavailable. For example, DTS occupies a large amount of read and write resources in the following cases: a large number of slow SQL queries are performed on the source database, the tables have no primary keys, or a deadlock occurs in the destination database. 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. For example, you can migrate data when the CPU utilization of the source and destination databases is less than 30%.
- DTS automatically creates a database in the destination RDS instance. However, if
the name of the source database is invalid, you must manually create a database in
the destination RDS instance before you configure the data migration task.
Note For more information about how to create a database and the database naming conventions, see Create accounts and databases for an ApsaraDB RDS for MySQL instance.
- To ensure data consistency, we recommend that you do not write data to the source MaxCompute project during full data migration.
- If a data migration task fails, DTS automatically resumes the task. Before you switch your workloads to the destination instance, stop or release the data migration task. Otherwise, the data in the source MaxCompute project will overwrite the data in the destination RDS instance after the task is resumed.
- MaxCompute does not support the PRIMARY KEY constraint. If network errors occur, DTS retries the data migration task. In this case, duplicate data records may be migrated to the destination tables that do not have primary keys.
- DTS cannot migrate incremental data from a MaxCompute project to an ApsaraDB RDS for
Note To ensure data consistency, we recommend that you do not write data to the source MaxCompute project during data migration.
Supported destination database types
You can use DTS to migrate data to the following types of MySQL databases:
- Self-managed database that is hosted on Elastic Compute Service (ECS)
- Self-managed database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway
- Self-managed database that is connected over Database Gateway
- ApsaraDB RDS for MySQL instance that is owned by the same Alibaba Cloud account as the MaxCompute project or a different Alibaba Cloud account from the MaxCompute project
|Migration type||Instance 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 Pricing.|
|Schema migration||DTS migrates the schemas of the required objects to the destination database. DTS
supports schema migration for views, tables, and databases.
Warning MaxCompute and MySQL are heterogeneous databases. DTS does not ensure that the schemas of the source and destination databases are consistent after schema migration. We recommend that you evaluate the impact of data type conversion on your business. For more information, see Data type mappings between heterogeneous databases.
|Full data migration||DTS migrates historical data of the required objects to the destination database.
Note During full data migration, concurrent INSERT operations cause fragmentation in the tables of the destination database. After full data migration is complete, the tablespace of the destination database is larger than that of the source database.
- Log on to the DTS console.
- In the left-side navigation pane, click Data Migration.
- At the top of the Migration Tasks page, select the region where the destination cluster resides.
- Configure the source and destination databases.
Section Parameter Description Source Database Instance Type Select MaxCompute. Instance Region Select the region where the source MaxCompute project resides. Project Enter the name of the MaxCompute project. You can search for a project on the Workspaces page in the DataWorks console. Destination Database Instance Type Select RDS Instance. Instance Region Select the region where the destination ApsaraDB RDS for MySQL instance resides. RDS Instance ID Select the ID of the destination ApsaraDB RDS for MySQL instance. Database Account Enter the database account of the destination ApsaraDB RDS for MySQL instance. The account must have the read and write permissions on the destination database. Database Password Enter the password of the destination database account.
After you specify the destination database parameters, click Test Connectivity next to Database Password to verify whether the specified parameters are valid.Note If the specified parameters are valid, the Passed message appears. If the Failed message appears, click Check next to Failed. Modify the destination database parameters based on the check results.
Encryption Select Non-encrypted or SSL-encrypted. If you want to select SSL-encrypted, you must enable SSL encryption for the RDS instance before you configure the data migration task. For more information, see Configure SSL encryption on an ApsaraDB RDS for MySQL instance.
- In the lower-right corner of the page, click Set Whitelist and Next. Note DTS adds the CIDR blocks of DTS servers to the whitelists of the source and destination instances. This ensures that DTS servers can connect to the destination instance.
- In the lower-right corner of the page, click Next. In this step, the permissions on the MaxCompute project are granted to the migration
account. The following figure shows an example.
- Select the migration types and the objects to be migrated.
Setting Description Select the migration types Select Schema Migration and Full Data Migration.Note DTS cannot migrate incremental data from a MaxCompute project to an ApsaraDB RDS for MySQL instance. Select the objects to be migrated
Select one or more objects from the Available section and click the icon to move the objects to the Selected section.Note
- You can select columns, tables, or databases as the objects to be migrated.
- By default, after an object is migrated to the destination database, the name of the object remains unchanged. You can use the object name mapping feature to change the names of the objects that are migrated to the destination database. For more information, see Object name mapping.
- If you use the object name mapping feature on an object, other objects that are dependent on the object may fail to be migrated.
Specify the retry time for failed connection to the source or destination database By default, if DTS fails to connect to the source or destination database, DTS retries within the next 12 hours. You can specify the retry time based on your needs. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data migration task. Otherwise, the data migration task fails.Note When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
- In the lower-right corner of the page, click Precheck.Notice
- Before you can start the data migration task, a precheck is performed. You can start the data migration task only after the task passes the precheck.
- If the task fails to pass the precheck, you can click the icon next to each failed item to view details.
- You can troubleshoot the issues based on the causes and run a precheck again.
- If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
- After the precheck is past, click Next.
- In the Confirm Settings dialog box, specify the Channel Specification parameter and select Data Transmission Service (Pay-As-You-Go) Service Terms.
- Click Buy and Start to start the data migration task.Note We recommend that you do not manually stop a data migration task. Otherwise, data migrated to the destination instance will be incomplete. You can wait until the data migration task automatically stops.
- Switch your workloads to the ApsaraDB RDS for MySQL instance.