Data Transmission Service:Migrate data from RDS MySQL to AnalyticDB for MySQL 3.0

Prerequisites

• You have created a destination AnalyticDB for MySQL 3.0 cluster. For more information, see Create a cluster.

• The storage space of the destination AnalyticDB for MySQL instance must be larger than the storage space that is used by the source RDS for MySQL instance.

Notes

Billing

Migration types

• Schema migration

  DTS migrates the schema definitions of the migration objects from the source database to the destination database.

  Note

  This is a heterogeneous data migration. During schema migration, DTS cannot perfectly map all data types. You must carefully evaluate the impact of data type mapping on your business. For more information, see Data type mappings between heterogeneous databases.

• Full migration

  DTS migrates all historical data of the migration objects from the source database to the destination database.

• Incremental migration

  After a full migration, DTS migrates incremental data updates from the source database to the destination database. Incremental data migration lets you smoothly migrate data without stopping your self-managed applications.

Supported SQL operations for incremental migration

Database account permissions

Procedure

1. Navigate to the migration task list page for the destination region using one of the following methods.

   From the DTS console

   1. Log on to the Data Transmission Service (DTS) console.

   2. In the navigation pane on the left, click Data Migration.

   3. In the upper-left corner of the page, select the region where the migration instance is located.

   From the DMS console

   Note

   The actual operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode console and Customize the layout and style of the DMS console.

   1. Log on to the Data Management (DMS) console.

   2. In the top menu bar, choose Data + AI > Data Transmission (DTS) > Data Migration.

   3. To the right of Data Migration Tasks, select the region where the migration instance is located.

2. Click Create Task to navigate to the task configuration page.

3. Configure the source and destination databases.

   Warning

   After you select the source and destination instances, we recommend that you carefully read the limits displayed at the top of the page. Otherwise, the task may fail or data inconsistency may occur.

   Category	Configuration	Description
   None	Task Name	DTS automatically generates a task name. We recommend that you specify a descriptive name for easy identification. The name does not need to be unique.
   Source Database	Select Existing Connection	To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured. Note In the DMS console, this parameter is named Select a DMS database instance.. If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.
   	Database Type	Select MySQL.
   	Connection Type	Select Cloud Instance.
   	Instance Region	Select the region where the source RDS MySQL instance resides.
   	Cross-account	This example shows a migration within the same Alibaba Cloud account. Select No.
   	RDS Instance ID	Select the ID of the source RDS MySQL instance.
   	Database Account	Enter the database account of the source RDS MySQL instance. For information about the required permissions, see Database account permissions.
   	Database Password	Enter the password for the database account.
   	Encryption	Select Non-encrypted or SSL-encrypted based on your database requirements. If you set this parameter to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Quickly enable SSL encryption using a cloud certificate.
   Destination Database	Select Existing Connection	To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured. Note In the DMS console, this parameter is named Select a DMS database instance.. If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.
   	Database Type	Select AnalyticDB MySQL 3.0.
   	Connection Type	Select Cloud Instance.
   	Instance Region	Select the region where the destination AnalyticDB for MySQL 3.0 cluster resides.
   	Instance ID	Select the ID of the destination AnalyticDB for MySQL 3.0 cluster.
   	Database Account	Enter the database account of the destination AnalyticDB for MySQL 3.0 cluster. For information about the required permissions, see Database account permissions.
   	Database Password	Enter the password for the database account.

4. After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page.

   Note

   • Ensure that the IP address segment of the DTS service is automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add DTS server IP addresses to a whitelist.

   • If the source or destination database is a self-managed database (the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.

5. Configure the task objects.

   1. On the Configure Objects page, configure the objects that you want to migrate.

      Configuration	Description
      Migration Types	If you want to perform a full migration, select both Schema Migration and Full Migration. To perform a migration without service interruption, select Schema Migration, Full Migration, and Incremental Migration. Note If you select Full Migration, all tables, including their schemas and data, can be migrated to the destination database. If you do not select Incremental Migration, do not write new data to the source instance during the data migration to ensure data consistency.
      Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks whether tables with the same names exist in the destination database. If no tables with the same names exist, the precheck is passed. If tables with the same names exist, an error is reported during the precheck, and the data migration task does not start. Note If a table in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the table in the destination database. For more information, see Object name mapping. Ignore Errors and Proceed: Skips the check for tables with the same names. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example: If the table schemas are consistent and a record in the destination database has the same primary key value as a record in the source database: During full migration, DTS keeps the record in the destination database. The record from the source database is not migrated. During incremental migration, DTS does not keep the record in the destination database. The record from the source database overwrites the record in the destination database. If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.
      DDL and DML Operations to Be Synchronized	Select the SQL operations for incremental migration at the instance level. For information about the supported operations, see Supported SQL operations for incremental migration. Note To select SQL operations for incremental migration at the database or table level, right-click a migration object in the Selected Objects box and select the desired SQL operations in the dialog box that appears.
      Merge Tables	If you select Yes, DTS adds the __dts_data_source column to each table to record data sources. For more information, see Enable multi-table merge. If you select No, this is the default option. Note The table merging feature is configured at the task level, not the table level. To merge some tables but not others, you must create two separate data migration tasks. Warning Do not perform DDL operations to change the schema of the source database or tables. Otherwise, data inconsistency or task failure may occur.
      Capitalization of Object Names in Destination Instance	You can configure the case sensitivity policy for the names of migrated objects, such as databases, tables, and columns, in the destination instance. By default, DTS default policy is selected. You can also choose to keep the case sensitivity consistent with the default policy of the source or destination database. For more information, see Case sensitivity of object names in the destination database.
      Source Objects	In the Source Objects box, click the objects to migrate, and then click to move them to the Selected Objects box. Note You can select migration objects at the granularity of database, table, or column. If you select tables as migration objects, other objects such as views, triggers, and stored procedures are not migrated to the destination database. If you select an entire database as the migration object, the following rules apply by default: If a table to be migrated in the source database has a primary key (single-column or multi-column), the primary key column is used as the distribution key. If a table to be migrated in the source database does not have a primary key, an auto-increment primary key column is automatically generated. This may cause data inconsistency between the source and destination databases.
      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 Individual table column mapping. 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 If you use the object name mapping feature, the migration of other objects that depend on the mapped object may fail. To filter data using a WHERE clause, right-click the table to be migrated in the Selected Objects box and set the filter condition in the dialog box that appears. For more information, see Set a filter condition. To select SQL operations for migration at the database or table level, right-click the migration object in the Selected Objects box and select the desired SQL operations in the dialog box that appears. You can also right-click a table to be migrated in the Selected Objects box and use the add column feature. For more information, see Add an additional column.

   2. Click Next: Advanced Settings to configure advanced parameters.

      Configuration	Description
      Dedicated Cluster for Task Scheduling	By default, DTS schedules tasks on a shared cluster. You do not need to select one. If you want more stable tasks, you can purchase a dedicated cluster to run DTS migration tasks.
      Copy the temporary table of the Online DDL tool that is generated in the source table to the destination database.	If you use Data Management (DMS) or gh-ost to perform online DDL changes in the source database, you can choose whether to migrate the data from the temporary tables generated by the online DDL changes. Important DTS tasks do not support using tools such as pt-online-schema-change to perform online DDL changes. Otherwise, the DTS task fails. The processing methods for each phase are as follows: The Schema Migration and Full Data Migration phases do not allow DDL operations that change the database or table structure. Therefore, they are not controlled by the online DDL policy. Schema Migration: Not controlled by the online DDL policy. Related temporary tables are created. Full Data Migration: Not controlled by the online DDL policy. The migration of temporary tables is not included in the full migration objects. All tables whose names match the regular expression (^_(.+)_(?:gho|new)$ or ^_(.+)_(?:ghc|del|old)$) are filtered out. Incremental Data Migration: Controlled by the online DDL policy. Yes: Migrates data changes from temporary tables (for example, _table_name_gho) generated by online DDL operations. No, Adapt to DMS Online DDL and No, Adapt to gh-ost: Filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules. Yes: Migrates the data from the temporary tables generated by online DDL changes. Note If online DDL changes generate a large amount of data in temporary tables, it may cause task latency. No, Adapt to DMS Online DDL: Does not migrate the data from the temporary tables generated by online DDL changes. It only migrates the original DDL statements executed using Data Management (DMS). Note This option causes tables in the destination database to be locked. No, Adapt to gh-ost: Does not migrate the data from the temporary tables generated by online DDL changes. It supports custom filtering rules. DTS filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules. You can modify the default regular expressions used to match shadow and useless tables as needed: Shadow table: ^_(.+)_(?:gho|new)$ Useless table: ^_(.+)_(?:ghc|del|old)$ Note This option causes tables in the destination database to be locked.
      Retry Time for Failed Connections	After the migration task starts, if the connection to the source or destination database fails, DTS reports an error and immediately begins to retry the connection. The default retry duration is 720 minutes. You can customize the retry time to a value from 10 to 1440 minutes. We recommend that you set the duration to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails. Note For multiple DTS instances that share the same source or destination, the network retry time is determined by the setting of the last created task. Because you are charged for the task during the connection retry period, we recommend that you customize the retry time based on your business needs, or release the DTS instance as soon as possible after the source and destination database instances are released.
      Retry Time for Other Issues	After the migration task starts, if a non-connectivity issue, such as a DDL or DML execution exception, occurs in the source or destination database, DTS reports an error and immediately begins to retry the operation. The default retry duration is 10 minutes. You can customize the retry time to a value from 1 to 1440 minutes. We recommend that you set the duration to more than 10 minutes. If the related operations succeed within the specified retry duration, the migration task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than the value of Retry Time for Failed Connections.
      Enable Throttling for Full Data Migration	During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Full Data Migration for Migration Types. You can also adjust the full migration speed after the migration instance is running.
      Enable Throttling for Incremental Data Migration	If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Incremental Data Migration for Migration Types. You can also adjust the incremental migration speed after the migration instance is running.
      Whether to delete SQL operations on heartbeat tables of forward and reverse tasks	Choose whether DTS writes heartbeat SQL information to the source database while the instance is running. Yes: Does not write heartbeat SQL information to the source database. The DTS instance may display latency. No: Writes heartbeat SQL information to the source database. This may interfere with source database operations like physical backups and cloning.
      Environment Tag	You can select an environment tag to identify the instance as needed. No selection is required for this example.
      Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
      Monitoring and Alerting	Select whether to set alerts and receive alert notifications based on your business needs. No: Does not set an alert. Yes: Configure alerts by setting an alert threshold and an alert notifications. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

   3. Click Next: Data Validation to configure a data validation task.

      For more information about the data validation feature, see Configure data validation.

   4. Optional: After you complete the preceding configurations, click Next: Configure Database and Table Fields to set the Type, Primary Key Column, Distribution Key, and partition key information (Partition Key, Partitioning Rules, and Partition Lifecycle) for the tables to be migrated in the destination database.

      Note

      • This step is available only if you select the Schema Migration option for Migration Types when you configure task objects. You can select All for Definition Status to make modifications.

      • You can select multiple columns for Primary Key Column to form a composite primary key. You must also select one or more columns from the Primary Key Column to use as the Distribution Key and Partition Key. For more information, see CREATE TABLE.

6. Save the task and run a precheck.

   • To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.

   • If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

   Note

   • Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.

   • If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.

   • If a warning is reported during the precheck:

     • For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.

     • For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.

7. Purchase the instance.

   1. When the Success Rate is 100%, click Next: Purchase Instance.

   2. On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

      Category	Parameter	Description
      New Instance Class	Resource Group Settings	Select the resource group to which the instance belongs. The default value is default resource group. For more information, see What is Resource Management?
      	Instance Class	DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

   3. After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.

   4. Click Buy and Start. In the OK dialog box that appears, click OK.

      You can view the progress of the migration task on the Data Migration Tasks list page.

      Note

      • If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.

      • If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.

FAQ

• During schema synchronization or migration, the following error occurs: only 500 dimension table allowed, current dimensionTableCount: 500. How do I resolve it?

  • Cause: In AnalyticDB for MySQL, the total number of tables includes both tables currently in use and tables in the recycle bin. If this total exceeds the limit, an error appears indicating that the table count limit has been exceeded. For more information, see Limits.

  • Solution:

    1. In your DTS task, check whether the number of tables being synchronized or migrated exceeds the maximum value shown in the error message.

    2. If the number of tables does not exceed the maximum, run the following commands to check whether deleted tables exist in the recycle bin. For more information, see Table recycle bin.

       -- Query the number of tables currently in use by the instance.
       SELECT COUNT(*) FROM INFORMATION_SCHEMA.tables;
       -- Query the number of tables in the recycle bin.
       SELECT COUNT(*) FROM INFORMATION_SCHEMA.KEPLER_META_RECYCLE_BIN;

    3. If you confirm that deleted tables exist in the recycle bin, run the following commands to clean them up.

       Important

       After you purge tables from the recycle bin, they cannot be recovered. Confirm that these tables are no longer needed.

       -- Delete all tables from the table recycle bin.
       PURGE RECYCLE_BIN ALL;
       -- Delete a specific table from the table recycle bin.
       PURGE RECYCLE_BIN TABLE <table name in ADB_RECYCLE_BIN database>;