Migrate data from PolarDB-X 1.0 to AnalyticDB for MySQL 3.0 - Data Transmission Service

This topic describes how to use Data Transmission Service (DTS) to migrate data from PolarDB-X 1.0 to AnalyticDB for MySQL 3.0.AnalyticDB for MySQL

Prerequisites

The source PolarDB-X 1.0 instance is created. For more information, see Create a PolarDB-X 1.0 instance.
Note
The storage type of the PolarDB-X 1.0 instance must be ApsaraDB RDS for MySQL, including custom instances and purchased instances. PolarDB for MySQL cannot be used as the storage type.
If you need to perform incremental migration, make sure that the character set of the data to be migrated is not utf8mb3. Otherwise, the incremental data migration will fail.
A target AnalyticDB for MySQL 3.0 cluster with storage space larger than the storage space used by the source PolarDB-X 1.0 instance. For more information, see Create a cluster.

Considerations

Note

During schema migration, DTS does not migrate foreign keys from the source database to the destination database.
During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If cascade updates or deletions are executed on the source database during data migration, data inconsistency may occur.

Type	Description
Limits on source	Bandwidth requirements: The server to which the source database belongs must have sufficient outbound bandwidth. Otherwise, the data migration speed is affected. 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 modify the tables in the destination database, such as renaming tables or columns, you can migrate up to 1,000 tables 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. If you need to migrate incremental data, make sure that the following requirements are met: The binary logging feature is enabled. The value of the binlog_row_image parameter is set to full. Otherwise, error messages are returned during precheck and the data migration task cannot be started. If you perform only incremental data migration, the binary logs of the source database must be stored for more than 24 hours. If you perform full data migration and incremental data migration, the binary logs of the source database must be stored for at least seven days. Otherwise, Data Transmission Service (DTS) may fail to obtain the binary logs and the task may fail. In exceptional circumstances, data inconsistency or loss may occur. After full data migration is complete, you can set the retention period to more than 24 hours. Make sure that you set the retention period of binary logs based on the preceding requirements. Otherwise, the Service Level Agreement (SLA) of DTS does not guarantee service reliability or performance. Limits on operations on the source database: During data migration, do not perform operations such as scaling, shrinking, migrating hot tables, changing shard keys, and changing DDL. Otherwise, data migration will fail. During full data migration and incremental data migration, DTS temporarily disables the constraint check and cascade operations on foreign keys at the session level. If cascade updates or deletions are executed on the source database during data migration, data inconsistency may occur. If you need to switch the network type of PolarDB-X 1.0 during migration, after the switch is successful, please adjust the network connection information of the migration link. If you perform only full data migration, do not write data to the source database during data migration. Otherwise, data inconsistency occurs. To ensure data consistency, we recommend that you select schema migration, full data migration, and incremental data migration. PolarDB-X 1.0 must be compatible with MySQL 5.7. The source PolarDB-X 1.0 instance version must be 5.2 or later.
Other limits	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. The destination database must have a custom primary key, or you must configure Primary Key Column in the Configurations for Databases, Tables, and Columns phase. Otherwise, data migration may fail. 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. Otherwise, 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 database. DTS attempts to resume data migration tasks that failed within the last seven days. Therefore, before you switch your business to the destination instance, make sure that you end or release the task, or revoke the write permissions of the DTS account on the destination instance by using the `revoke` command. Otherwise, the data in the source database overwrites the data in the destination database after the task is resumed. If the destination AnalyticDB for MySQL V3.0 cluster is being backed up while the DTS task is running, the DTS task fails. If a DTS task fails to run, DTS technical support will try to restore the task within 8 hours. During the restoration, the task may be restarted, and the parameters of the task may be modified. Note Only the parameters of the task may be modified. The parameters of databases are not modified. The parameters that may be modified include but are not limited to the parameters in the "Modify instance parameters" section of the Modify the parameters of a DTS instance topic.
Other precautions	DTS periodically updates the `dts_health_check`.`ha_health_check` table in the source database to advance the binlog position.

Description for fees

Migration type	Link configuration fee	Data transfer cost
Schema migration and full data migration	Free of charge.	When you migrate data from Alibaba Cloud over the Internet, you are charged for the outbound traffic. 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 the selected objects from the source database to the destination database.
Full data migration
DTS migrates the historical data of required 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 allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.

SQL operations that can be incrementally migrated

Operation type	SQL statement
DML	INSERT, UPDATE, DELETE Note When data is written to the destination AnalyticDB for MySQL V3.0 cluster, the UPDATE statement is automatically converted to the REPLACE INTO statement. If the UPDATE statement is executed on the primary key, the UPDATE statement is converted to the DELETE and INSERT statements.

Permissions required for database accounts

Database	Schema migration	Full migration	Incremental migration
PolarDB-X 1.0 instance	The SELECT permission	The SELECT permission	The REPLICATION SLAVE permission, the REPLICATION CLIENT permission, and the SELECT permission on the objects to migrate. Note For information about how to grant permissions, see Account permission issues during data synchronization.
AnalyticDB for MySQL 3.0 cluster	Access control list

For information about how to create a database account and grant permissions to the account, see the following topics:

For PolarDB-X 1.0 instances, see Account Management.
AnalyticDB for MySQL 3.0 cluster, see Create a database account.

Data type mappings

For more information, see Data type mappings for schema migration.

Procedure

Use one of the following methods to go to the Data Migration page and select the region in which the data migration instance resides.
DTS console
1. Log on to the DTS console.
2. In the left-side navigation pane, click Data Migration.
3. In the upper-left corner of the page, select the region in which the data migration instance resides.
DMS console
Note
The actual operation 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.
1. Log on to the DMS console.
2. In the top navigation bar, move the pointer over Data + AI > DTS (DTS) > Data Migration .
3. From the drop-down list to the right of Data Migration Tasks, select the region in which the data synchronization instance resides.
Click Create Task to go to the task configuration page.

Configure the source and destination databases. The following table describes the parameters.

Warning

After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

Category	Configuration	Description
N/A	Task Name	The name of the DTS task. DTS automatically generates a task name. We recommend that you specify an informative name that makes it easy to identify the task. You do not need to specify a unique task name.
Source Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	Select PolarDB-X 1.0.
	Access Method	Select Cloud Instance.
	Instance Region	Select the region where the source PolarDB-X 1.0 instance resides.
	Replicate Data Across Alibaba Cloud Accounts	In this example, a database instance of the current Alibaba Cloud account is used. Select No.
	Instance ID	Select the ID of the source PolarDB-X 1.0 instance.
	Database Account	Enter the database account of the source PolarDB-X 1.0 instance. For information about the permissions that are required for the account, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.
Destination Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
	Database Type	Select AnalyticDB MySQL 3.0.
	Access Method	Select Cloud Instance.
	Instance Region	Select the region where your target AnalyticDB for MySQL 3.0 cluster is located.
	Instance ID	Select the ID of the target AnalyticDB for MySQL 3.0 cluster.
	Database Account	Enter the database account of the destination AnalyticDB for MySQL 3.0 cluster. For permission requirements, see Permissions required for database accounts.
	Database Password	The password that is used to access the database instance.

After the configuration is complete, click Test Connectivity and Proceed at the bottom of the page.
Note
Make sure that the IP address ranges of DTS servers can be 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 the IP address ranges of DTS servers.

Configure the objects to be migrated.

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

Configuration	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 Schema Migration, make sure a database and a table are created in the destination database to receive data and the object name mapping feature is enabled in Selected Objects. 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.
DDL and DML Operations to Be Synchronized	Select the SQL operations for incremental migration at the instance level. For information about the supported migration operations, see SQL operations that can be incrementally migrated. Note To select SQL operations for incremental migration at the database or table level, right-click the migration object in Selected Objects and select the SQL operations to be migrated in the pop-up box.
Merge Tables	Select Yes: DTS adds a `__dts_data_source` column to each table to store the data source. For more information, see Enable multi-table merge. Note If you set this parameter to Yes, all the selected source tables in the task are merged into a single destination table. To merge only the data source columns of specific tables, you can create two data migration tasks. Select No: This is the default option. Warning We recommend that you do not perform DDL operations to change the schemas of source databases or tables. Otherwise, data inconsistency may occur or the migration task fails.
Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that use 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 If the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. 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, and a data record has the same primary key as an existing data record in the destination database, the following scenarios may occur: During full data migration, DTS does not migrate the data record to the destination database. The existing data record in the destination database is retained. During incremental data migration, DTS migrates the data record to the destination database. The existing data record in the destination database is overwritten. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
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 of 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 columns, tables, or databases as the objects to be migrated. If you select a table as the migration object, other objects (such as views, triggers, and stored procedures) are not migrated to the destination database. If you select a database as the migration object, the default settings are as follows: If the tables to be migrated have one or more primary key columns, including single and multiple column primary keys, this primary key is used as the distribution key. If the tables to be migrated do not have a primary key, an auto increment primary key is automatically generated. In this case, data inconsistency may occur between the source and destination databases.
Selected Objects	To rename a single object in the destination instance, right-click the object in the Selected Objects section. For more information, see Rename objects one by one. To rename multiple objects at a time in the destination instance, click Edit in the upper-right corner of the Selected Objects section. For more information, see Rename objects in batches. Note 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 set a WHERE condition to filter data, right-click the table to be migrated in Selected Objects and set a filter condition in the dialog box that appears. For more information, see Configure filter conditions. To select SQL operations for migration at the database or table level, right-click the object to be migrated in Selected Objects and select the SQL operations to be migrated in the dialog box that appears.

Click Next: Advanced Settings to configure advanced settings.

Configuration	Description
Dedicated Cluster for Task Scheduling	By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. If you want to improve the stability of data migration tasks, purchase a dedicated cluster. For more information, see What is a DTS dedicated cluster.
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 retry time range. Valid values: 10 to 1,440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later 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 the earliest opportunity after the source database and destination instance are released.
Retry Time for Other Issues	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Important The value of the Retry Time for Other Issues parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
Enable Throttling for Full Data Migration	Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Full Data Migration for the Migration Types parameter.
Enable Throttling for Incremental Data Migration	Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is selected.
Configure ETL	Specifies whether to enable 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.
Monitoring and Alerting	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 receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see the Configure monitoring and alerting when you create a DTS task section of the Configure monitoring and alerting topic.

Optional: After the preceding configuration is complete, click Next: Configure Database and Table Fields to set the Type, Primary Key Column, Distribution Key, and partition information (Partition Key, Partitioning Rules, and Partition Lifecycle) for the tables to be migrated in the destination database.
Note
- This step is available only when Migration Types includes Schema Migration. You can set Definition Status to All and then make modifications.
- You can select multiple columns to form a composite Primary Key Column, and you need to select one or more columns from the Primary Key Column as the Distribution Key and Partition Key. For more information, see CREATE TABLE.

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 analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.
- If an alert is triggered for an item during the precheck:
  If an 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.

Purchase an instance.

Wait until 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 Instance classes 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. In the message that appears, click OK.
You can view the progress of the task on the Data Migration page.
Note
- If a data migration task cannot be used to migrate incremental data, the task automatically stops. The Completed is displayed in the Status section.
- If a data migration task can be used to migrate incremental data, the task does not automatically stop. The incremental data migration task never stops or completes. The Running is displayed in the Status section.