Data Transmission Service (DTS) supports migrating data from SQL Server (including ApsaraDB RDS for SQL Server and self-managed SQL Server) to AnalyticDB for MySQL for real-time data analysis.
Supported source databases
You can migrate data from the following SQL Server source databases to AnalyticDB for MySQL. This topic describes the configuration process using an RDS for SQL Server instance as the source database. The process for other data sources is similar.
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RDS for SQL Server instances.
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Self-managed databases:
- Self-managed database with a public IP address
- 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
Prerequisites
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This migration task can be configured only in the new console.
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A source RDS SQL Server instance has been created. For a list of supported versions, see Overview of migration solutions. To create an instance, see Create an ApsaraDB RDS for SQL Server instance.
ImportantIf the RDS SQL Server instance runs SQL Server 2008 or SQL Server 2008 R2, incremental data migration is not supported.
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A target AnalyticDB for MySQL cluster has been created. For instructions, see Create a cluster.
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The storage capacity of the target AnalyticDB for MySQL cluster must be greater than that of the source RDS SQL Server instance.
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If the source instance meets any of the following conditions, split it into multiple migration tasks.
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The instance contains more than 10 databases.
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Log backups for a single database occur more than once per hour.
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More than 100 DDL operations occur on a single database per hour.
Log volume for a single database exceeds 20 MB/s
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CDC (change data capture) is required for more than 1,000 tables.
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Notes
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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 limits |
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Other limits |
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Special cases |
If the source instance is an RDS for SQL Server instance, DTS creates an |
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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DTS can migrate the following schema objects: schemas, tables, views, functions, and procedures.
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DTS cannot migrate the following objects: assemblies, service brokers, full-text indexes, full-text catalogs, distributed schemas, distributed functions, Common Language Runtime (CLR) stored procedures, CLR scalar-valued functions, CLR table-valued functions, internal tables, systems, or aggregate functions.
WarningIn migrations between heterogeneous databases, data types might not correspond one-to-one. This can cause task failures or data loss. Carefully evaluate the business impact of data type mappings. For more information, see Data type mapping for heterogeneous databases.
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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, and DELETE Note
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DDL |
Note
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Database account permissions
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Database |
Schema migration |
Full data migration |
Incremental data migration |
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RDS SQL Server instance |
Read permissions on objects to be migrated |
Read permissions on objects to be migrated |
Owner permissions on objects to be migrated |
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AnalyticDB for MySQL cluster |
Read and write permissions |
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To create and grant permissions to a database account, see the following topics:
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For an RDS SQL Server instance, see Create standard, privileged, and global read-only accounts and Modify the permissions of an account.
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For an AnalyticDB for MySQL cluster, see Create a database account.
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 SQL Server.
Connection Type
Select Alibaba Cloud Instance.
Instance Region
Select the region where the source RDS SQL Server instance resides.
Replicate Data Across Alibaba Cloud Accounts
This example shows how to migrate data within the same Alibaba Cloud account. Select No.
RDS Instance ID
Select the ID of the source RDS SQL Server instance.
Database Account
Enter the database account for the source RDS SQL Server instance. For details on required permissions, see Permission requirements for database accounts.
Database Password
Enter the password for the database account.
Encryption
Select Non-encrypted or SSL-encrypted based on your business requirements.
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If SSL encryption is disabled for the source database, select Non-encrypted.
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If SSL encryption is enabled for the source database, select SSL-encrypted. By default, DTS trusts the server certificate.
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 resides.
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 details on required permissions, see Permission requirements 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.
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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.
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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.
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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.
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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 of Conflicting 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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Schema Mapping Mode of Source and Destination Databases
Select a schema mapping mode as needed to map the schemas between the source and destination databases.
WarningTables in different schemas of the source database cannot have the same name. Otherwise, data inconsistency or task failure may occur.
SQL Server Incremental Synchronization Mode
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Log-based Parsing for Non-heap Tables and CDC-based Incremental Synchronization for Heap Tables (Hybrid Log-based Parsing):
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Advantages:
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Supports scenarios that involve source heap tables, tables without primary keys, compressed tables, or tables with computed columns.
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Provides high link stability. This mode can obtain complete DDL statements and supports a wide range of DDL scenarios.
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Disadvantages:
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DTS creates the `dts_cdc_sync_ddl` trigger, the `dts_sync_progress` heartbeat table, and the `dts_cdc_ddl_history` DDL storage table in the source database. It also enables database-level CDC and CDC for some tables.
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You cannot execute `SELECT INTO`, `TRUNCATE`, or `RENAME COLUMN` statements on tables with CDC enabled in the source database. You cannot manually delete triggers created by DTS in the source database.
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Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported):
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Advantage:
This mode is non-intrusive to the source database.
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Disadvantage:
This mode does not support scenarios that involve source heap tables, tables without primary keys, compressed tables, or tables with computed columns.
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Polling and querying CDC instances for incremental synchronization:
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Advantages:
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Supports full and incremental migration when the source database is Amazon RDS for SQL Server, Azure SQL Database, Azure SQL Managed Instance, Azure SQL Server on Virtual Machine, or Google Cloud SQL for SQL Server.
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This mode uses the native CDC component of SQL Server to obtain incremental data, which improves the stability of incremental migration and reduces network bandwidth usage.
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Disadvantages:
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The source database account used by the DTS instance must have the permissions to enable CDC. Incremental data migration has a latency of about 10 seconds.
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When you migrate multiple tables across multiple databases, you may encounter stability and performance issues.
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NoteThis parameter is available only if you select Incremental Data Migration for the Migration Types parameter.
The maximum number of tables for which CDC is enabled that DTS supports.
You can set a limit on the number of CDC-enabled tables for the current migration instance based on your business requirements. The default value is 1,000.
NoteThis parameter is not available if you set SQL Server Incremental Synchronization Mode to Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported).
Select DDL and DML to Sync at the Instance Level
Select the SQL operations for incremental migration at the instance level. For information about the supported operations, see SQL operations supported for incremental migration.
NoteTo 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.
Source Objects
In the Source Objects box, click the objects to migrate, and then click
to move them to the Selected Objects box.NoteThis scenario is a migration between heterogeneous databases. Therefore, the granularity for selecting migration objects is table. Other objects such as views, triggers, and stored procedures are not migrated to the destination database.
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.
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If you use the object name mapping feature, the migration of other objects that depend on the renamed object may fail.
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To set a WHERE condition to filter data, right-click the table to be migrated in the Selected Objects section and specify the filter condition in the dialog box that appears. For instructions, see Set filter conditions.
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To select SQL operations to be migrated at the database or table level, right-click the migration object in the Selected Objects section and select the desired SQL operations in the dialog box that appears.
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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.
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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.
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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.
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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 example does not require you to select a tag.
Configure ETL
Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values:
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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.
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No: Disables 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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Click Next: Data Validation to configure a data validation task.
For more information about the data validation feature, see Configure data validation.
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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.
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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 an 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.
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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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