The Data Transmission Service (DTS) synchronizes data from RDS SQL Server to AnalyticDB for MySQL. This enables easy data transmission for real-time analytics.
Prerequisites
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You have created an RDS SQL Server instance. For supported versions, see Synchronization overview. To create an instance, see Quickly create and use an RDS SQL Server instance.
ImportantIn hybrid log parsing mode, where SQL Server Incremental Synchronization Mode is set to Use log parsing for incremental synchronization of non-heap tables and CDC for incremental synchronization of heap tables, the following source database versions are supported:
Enterprise or Enterprise Evaluation Edition: Versions 2012, 2014, 2016, 2019, or 2022.
Standard Edition: Versions 2016, 2019, or 2022.
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You have created a target AnalyticDB for MySQL cluster. For details, see Create a cluster.
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The storage space of the target AnalyticDB for MySQL cluster must be larger than that of the source RDS SQL Server instance.
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Split the synchronization into multiple tasks if any of the following conditions apply to the source instance:
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The number of databases exceeds 10.
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Log backups are performed on a single database more than once per hour.
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DDL operations are performed on a single database more than 100 times per hour.
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The log volume of a single database exceeds 20 MB/s.
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Change Data Capture (CDC) needs to be enabled for more than 1,000 tables.
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Important notes
During schema synchronization, DTS does not synchronize foreign keys from the source database to the destination database.
During full and incremental synchronization, 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.
Type | Description |
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 a |
Billing
Synchronization type | Pricing |
Schema synchronization and full data synchronization | Free of charge. |
Incremental data synchronization | Charged. For more information, see Billing overview. |
Supported synchronization topologies
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One-way one-to-one synchronization
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One-way one-to-many synchronization
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One-way cascade synchronization
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One-way many-to-one synchronization
For more information about each topology, see Synchronization topologies.
Supported SQL operations
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Operation type |
SQL statements |
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DML |
INSERT, UPDATE, DELETE Note
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DDL |
Note
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Procedure
Go to the data synchronization task list page in the destination region. You can do this in one of two ways.
DTS console
Log on to the DTS console.
In the navigation pane on the left, click Data Synchronization.
In the upper-left corner of the page, select the region where the synchronization instance is located.
DMS console
NoteThe actual steps may vary depending 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.
Log on to the DMS console.
In the top menu bar, choose .
To the right of Data Synchronization Tasks, select the region of the synchronization instance.
Click Create Task to open the task configuration page.
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Configure the source and destination databases.
WarningAfter you select the source and destination instances, review the Limits 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
Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.
NoteIn the DMS console, this configuration item is Select a DMS database instance.
If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.
Database Type
Select SQL Server.
Connection Type
Select Cloud instance.
Instance Region
Select the region where your source RDS SQL Server instance resides.
Replicate Data Across Alibaba Cloud Accounts
This example uses the same Alibaba Cloud account. Select No.
RDS Instance ID
Select your source RDS SQL Server instance ID.
Database Account
Enter the database account for your source RDS SQL Server instance. This account must have ownership permissions on the objects to synchronize.
Database Password
Enter the password for the specified database account.
Encryption
Select Non-encrypted or SSL-encrypted as needed.
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If SSL encryption is not enabled for the source database, select Non-encrypted.
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If SSL encryption is enabled for the source database, select SSL-encrypted. DTS trusts the server-side certificate by default.
Destination Database
Select Existing Connection
Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured.
NoteIn the DMS console, this configuration item is Select a DMS database instance.
If you have not registered the database instance 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 your destination AnalyticDB for MySQL cluster resides.
Instance ID
Select your destination AnalyticDB for MySQL cluster ID.
Database Account
Enter the database account for your destination AnalyticDB for MySQL cluster. This account must have read and write permissions.
Database Password
Enter the password for the specified database account.
After completing the configuration, click Test Connectivity and Proceed at the bottom of the page.
NoteEnsure that you add the CIDR blocks of the DTS servers (either automatically or manually) to the security settings of both the source and destination databases to allow access. For more information, see Add the IP address whitelist of DTS servers.
If the source or destination is a self-managed database (i.e., the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.
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Configure the task objects.
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On the Configure Objects page, specify the objects to synchronize.
Configuration
Description
Synchronization Types
DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.
NoteIf you select Full Synchronization, tables for which a CREATE TABLE statement was run (both schema and data) can be synchronized to the destination database.
Processing Mode of Conflicting Tables
Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful.
NoteIf you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Database Table Column Name Mapping.
Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database.
WarningSelecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example:
If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database:
During full data synchronization, DTS retains the destination record and skips the source record.
During incremental synchronization, DTS overwrites the destination record with the source record.
If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.
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
Log-based Parsing for Non-heap Tables and CDC-based Incremental Synchronization for Heap Tables (Hybrid Log-based Parsing):
Advantages:
Supports scenarios with source database heap tables, tables without primary keys, compressed tables, and tables with computed columns.
High link stability. This mode can obtain complete DDL statements and supports a wide range of DDL scenarios.
Disadvantages:
DTS creates the trigger `dts_cdc_sync_ddl`, the heartbeat table `dts_sync_progress`, and the DDL storage table `dts_cdc_ddl_history` in the source database. It also enables database-level Change Data Capture (CDC) and partial table CDC.
You cannot execute
SELECT INTO,TRUNCATE, andRENAME COLUMNstatements on tables for which CDC is enabled in the source database. Triggers created by DTS in the source database cannot be manually deleted.
Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported):
Advantages:
This mode is non-intrusive to the source database.
Disadvantages:
Does not support scenarios with source database heap tables, tables without primary keys, compressed tables, or tables with computed columns.
Polling and querying CDC instances for incremental synchronization:
Advantages:
Supports full and incremental synchronization 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.
Uses the native SQL Server CDC component to obtain incremental data, which makes incremental synchronization more stable and uses less network bandwidth.
Disadvantages:
The source database account used by the DTS instance must have the permission to enable CDC. Incremental data synchronization has a latency of about 10 seconds.
In scenarios involving synchronization of multiple databases and tables, there may be risks of stability and performance issues.
The maximum number of tables for which CDC is enabled that DTS supports.
Set the maximum number of tables for which CDC can be enabled for the current synchronization instance as needed. The default value is 1000.
NoteThis configuration item is unavailable when SQL Server Incremental Synchronization Mode is set to Incremental Synchronization Based on Logs of Source Database (Heap tables are not supported).
Select DDL and DML for Instance-Level Synchronization
Select SQL operations to synchronize at the instance level. For supported operations, see Supported SQL operations.
NoteTo select SQL operations for a database or table, right-click a synchronization object in the Selected Objects box and select the SQL operations from the dialog box that appears.
Source Objects
In the Source Objects box, click the objects, and then click
to move them to the Selected Objects box.NoteThis scenario involves synchronization between heterogeneous databases. Therefore, you can select objects only at the table level. Other objects, such as views, triggers, and stored procedures, are not synchronized to the destination database.
Selected Objects
To rename a single object in the destination instance, right-click the object in the Selected Objects box. For more information, see Map a single object name.
To rename multiple objects in bulk, click Batch Edit in the upper-right corner of the Selected Objects box. For more information, see Map multiple object names in bulk.
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To select SQL operations at the database or table level, right-click a synchronized object in Selected Objects and select the required operations in the pop-up dialog.
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To filter data using a WHERE condition, right-click a table in Selected Objects and set the filter condition in the pop-up dialog. For instructions, see Set filter conditions.
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Using object name mapping may cause dependent objects to fail synchronization.
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Click Next: Advanced Settings.
Configuration
Description
Dedicated Cluster for Task Scheduling
By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.
Retry Time for Failed Connections
If the connection to the source or destination database fails after the synchronization task starts, 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 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails.
NoteIf multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances.
DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.
Retry Time for Other Issues
If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails.
ImportantThe value of Retry Time for Other Issues must be less than that of Retry Time for Failed Connections.
Enable Throttling for Full Data Synchronization
During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s).
NoteThis parameter is available only if Synchronization Types is set to Full Data Synchronization.
You can also adjust the rate of full data synchronization when the synchronization instance is running.
Enable Throttling for Incremental Data Synchronization
You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).
Environment Tag
Select an environment label to identify the instance. Not 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:
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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
Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts.
No: No alerts are configured.
Yes: Configures alerts. You must also set the alert threshold and alert notifications. For more information, see Configure monitoring and alerting during task configuration.
Click Data Verification to configure a data verification task.
To use the data verification feature, see Configure data verification.
Optional: After you complete the configuration, 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 sync in the destination database.
NoteThis step is available only if you select the Schema Synchronization checkbox for Synchronization Types during task object configuration. You can set Definition Status to All to make modifications.
You can use the Primary Key Column to specify a composite primary key that consists of multiple columns. You must then select one or more columns from the Primary Key Column to serve as the Distribution Key and Partition Key. For more information, see CREATE TABLE.
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Save the task and perform a precheck.
To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.
If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.
NoteBefore a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.
If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.
If the precheck generates warnings:
For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.
For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.
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Purchase the instance.
When the Success Rate reaches 100%, click Next: Purchase Instance.
On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.
Category
Parameter
Description
New Instance Class
Billing Method
Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks.
Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.
Resource Group Settings
The resource group to which the instance belongs. The default is default resource group. For more information, see What is Resource Management?.
Instance Class
DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.
Subscription Duration
In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years.
NoteThis option appears only when the billing method is Subscription.
Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.
Click Buy and Start, and then click OK in the OK dialog box.
You can monitor the task progress on the data synchronization page.