This topic describes how to migrate full data from a self-managed TiDB database to an ApsaraDB RDS for MySQL instance by using Data Transmission Service (DTS).
Prerequisites
An Create an ApsaraDB RDS for MySQL instance instance is created.Notice
- The destination ApsaraDB RDS for MySQL instance resides in the China (Hangzhou), China (Shanghai), China (Qingdao), China (Beijing), China (Shenzhen), China (Zhangjiakou), China (Hong Kong), Singapore (Singapore), US (Silicon Valley), or US (Virginia) region.
- The available storage space of the destination ApsaraDB RDS for MySQL instance is larger than the total size of the data in the self-managed TiDB database.
Precautions
- 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%.
- The tables to be migrated in the source database must have PRIMARY KEY or UNIQUE constraints and all fields must be unique. Otherwise, the destination database may contain duplicate data records.
- 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. - DTS automatically creates a destination database in the ApsaraDB RDS for MySQL instance.
However, if the name of the source database is invalid, you must manually create a
database in the ApsaraDB RDS for MySQL instance before you configure the data migration
task.
Note For more information about the naming conventions of ApsaraDB RDS for MySQL databases and how to create a database, see Create a database on an ApsaraDB RDS for MySQL instance.
- 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 instance will overwrite the data in the destination instance after the task is resumed.
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 Pricing. |
Migration types
Migration type | Description |
---|---|
Schema migration | DTS migrates the schemas of required objects to the destination database. DTS supports
schema migration for views, tables, and databases.
Warning TiDB 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 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 size
of the used tablespace of the destination database is larger than that of the source
database.
|
Preparations
If a whitelist is configured for the TiDB database, you must add the CIDR blocks of DTS servers to the whitelist of the database. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.