Use Data Transmission Service (DTS) to migrate data from PolarDB-X 2.0 to AnalyticDB for MySQL 3.0, enabling you to quickly build internal systems for business intelligence (BI), interactive queries, and real-time reports.
Prerequisites
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You have created a source PolarDB-X 2.0 instance.
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You have a target AnalyticDB for MySQL 3.0 cluster. For more information, see Create a cluster.
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The target AnalyticDB for MySQL 3.0 cluster must have more storage space than is used by the source PolarDB-X 2.0 instance.
Limitations
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During schema migration, DTS does not migrate foreign keys from the source database to the destination database.
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During full and incremental migration, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. If cascade update or delete operations occur in the source database while the task is running, data inconsistency may occur.
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Type |
Description |
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Source database limitations |
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Other limitations |
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Other precautions |
DTS periodically updates the |
Billing
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Migration type |
Instance configuration fee |
Internet traffic fee |
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Schema migration and full data migration |
Free of charge. |
When the Access Method parameter of the destination database is set to Public IP Address, you are charged for Internet traffic. For more information, see Billing overview. |
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Incremental data migration |
Charged. For more information, see Billing overview. |
Migration types
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Schema migration
DTS migrates the schema definitions of the migration objects from the source database to the destination database.
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Full migration
DTS migrates all historical data of the specified migration objects from the source database to the destination database.
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Incremental migration
After a full migration is complete, DTS migrates incremental data updates from the source database to the destination database. Incremental migration lets you smoothly migrate data without interrupting your self-managed applications.
Supported SQL operations for incremental migration
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Operation type |
SQL statement |
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DML |
INSERT, UPDATE, DELETE Note
When data is written to AnalyticDB for MySQL, UPDATE statements are automatically converted to REPLACE INTO statements. If the primary key is updated, the statement is converted to a DELETE statement and an INSERT statement. |
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DDL |
CREATE TABLE, DROP TABLE, RENAME TABLE, TRUNCATE TABLE, ADD COLUMN, MODIFY COLUMN, DROP COLUMN Important
A RENAME TABLE operation may cause data inconsistency. For example, if you select only one table as the migration object and rename the table in the source instance during migration, the data of this table is not migrated to the destination database. To prevent this issue, select the entire database to which the table belongs as the migration object when you configure the data migration task. Make sure that the databases to which the table belongs before and after the RENAME TABLE operation are both included in the migration objects. |
Database account permissions
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Database |
Schema migration |
Full data migration |
Incremental data migration |
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PolarDB-X 2.0 |
SELECT permission |
SELECT permission |
The REPLICATION SLAVE, REPLICATION CLIENT, and SELECT permissions on the objects to migrate. Note
For more information about how to grant permissions, see Account permission issues during data synchronization. |
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AnalyticDB for MySQL 3.0 |
read and write permissions |
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To create a database account and grant permissions:
AnalyticDB for MySQL 3.0: Create a database account.
Data type mappings
For details, see Data type mappings for initial schema synchronization.
Procedure
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Navigate to the migration task list page for the destination region using one of the following methods.
From the DTS console
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Log on to the Data Transmission Service (DTS) console.
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In the navigation pane on the left, click Data Migration.
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In the upper-left corner of the page, select the region where the migration instance is located.
From the DMS console
NoteThe 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.
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Log on to the Data Management (DMS) console.
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In the top menu bar, choose .
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To the right of Data Migration Tasks, select the region where the migration instance is located.
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Click Create Task to navigate to the task configuration page.
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Configure the source and destination databases.
WarningAfter 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
Parameter
Description
N/A
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
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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.
NoteIn the DMS console, this parameter is named Select a DMS database instance..
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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 PolarDB-X 2.0.
Connection Type
Select Alibaba Cloud Instance.
Instance Region
Select the region where the source PolarDB-X 2.0 instance is located.
Replicate Data Across Alibaba Cloud Accounts
This example is for a migration within the same Alibaba Cloud account. Select No.
Instance ID
Select the ID of the source PolarDB-X 2.0 instance.
Database Account
Enter the database account of the source PolarDB-X 2.0 instance. For information about the required permissions, see Permissions required for database accounts.
Database Password
Enter the password for the database account.
Destination Database
Select Existing Connection
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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.
NoteIn the DMS console, this parameter is named Select a DMS database instance..
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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 for MySQL 3.0.
Connection Type
Select Alibaba Cloud Instance.
Instance Region
Select the region where the destination AnalyticDB for MySQL 3.0 cluster is located.
Instance ID
Select the ID of the destination AnalyticDB for MySQL 3.0 cluster.
Database Account
Enter the database account for the destination AnalyticDB for MySQL 3.0 cluster. For information about the required permissions, see Permissions required for database accounts.
Database Password
Enter the password for the database account.
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After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page.
NoteEnsure that the DTS service IP address segments are 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.
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Configure the task objects.
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On the Configure Objects page, configure the objects that you want to migrate.
Parameter
Description
Migration Types
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If you want to perform a full migration, select both Schema Migration and Full Migration.
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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.
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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 for Existing Destination Tables
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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.
NoteIf 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.
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Ignore Errors and Proceed: Skips the check for tables with the same names.
WarningSelecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example:
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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:
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During full migration, DTS keeps the record in the destination database. The record from the source database is not migrated.
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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.
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If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.
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Table Merging
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If you select Yes, DTS adds the
__dts_data_sourcecolumn to each table to record data sources. For more information, see Enable multi-table merge. -
If you select No, this is the default option.
NoteThe 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.
WarningDo not perform DDL operations to change the schema of the source database or tables. Otherwise, data inconsistency or task failure may occur.
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 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.
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If you select an entire database as the migration object, the following rules apply by default:
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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.
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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.
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Selected Objects
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To change the name of a single migration object in the target instance, right-click the object in the Selected Objects box. For more information, see Map individual schema, table, and column names.
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To change the names of multiple migration objects in the target instance, click Selected Objects in the upper-right corner of the Batch Edit box. For more information, see Map multiple schema, table, and column names.
Note-
If you use the object name mapping feature, other objects that depend on the renamed object may fail to migrate.
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To filter data with a WHERE clause, right-click a table in the Selected Objects box and specify the filter conditions in the dialog box that appears. For more information, see Set filter conditions.
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To select the SQL operations to migrate at the database or table level, right-click a migration object in the Selected Objects box. In the dialog box that appears, select the desired SQL operations.
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Click Next: Advanced Settings to configure advanced parameters.
Parameter
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.
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.
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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.
ImportantThe 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.
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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.
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You can also adjust the incremental migration speed after the migration instance is running.
Environment Tag
You can select an environment tag to identify the instance based on your requirements. This is not required for this example.
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.
Configure ETL
Based on your business needs, select whether to configure the ETL feature to process data.
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Yes: Configures the ETL feature. You must also enter data processing statements in the text box.
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No: Does not configure the ETL feature.
Monitoring and Alerting
Select whether to set alerts and receive alert notifications based on your business needs.
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No: Does not set an alert.
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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.
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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.
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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.
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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.
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Save the task and run a precheck.
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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.
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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.
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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.
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If a warning is reported during the precheck:
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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.
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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.
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Purchase the instance.
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When the Success Rate is 100%, click Next: Purchase Instance.
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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.
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After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.
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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.
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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.
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