Data synchronization between AnalyticDB for MySQL 3.0 clusters-Data Transmission Service(DTS)-阿里云帮助中心

This topic describes how to use Data Transmission Service (DTS) to synchronize data between AnalyticDB for MySQL 3.0 clusters.

Prerequisites

You have created a target AnalyticDB for MySQL 3.0 cluster with storage space greater than the used storage space of the source AnalyticDB for MySQL 3.0 cluster.
The change data capture (CDC) feature is enabled for the source AnalyticDB for MySQL 3.0 cluster, and the binary log is enabled for the tables that you want to synchronize.
Note
- If the AnalyticDB for MySQL 3.0 cluster has an engine version earlier than 3.2.1.0, you must first upgrade it.
- The XUANWU_V2 table does not support enabling the binary log. Therefore, you cannot use DTS to synchronize data or perform incremental migration for XUANWU_V2 tables between AnalyticDB for MySQL clusters.

Limitations

Note

During schema synchronization, DTS does not synchronize foreign keys from the source database to the destination database.
During full data synchronization and incremental data synchronization, DTS temporarily disables constraint checks and foreign key cascade operations at the session level. If you perform cascade update or delete operations on the source database while the task is running, data inconsistency may occur.

Type	Description
Source database limitations	Bandwidth requirement: The server that hosts the source database must have sufficient outbound bandwidth. Otherwise, the data synchronization speed is affected. The AnalyticDB for MySQL 3.0 cluster must have an engine version of 3.2.1.0 or later. Tables to be synchronized must have a unique, custom primary key. Otherwise, the destination database may contain duplicate data. Note If the primary key of a table to be synchronized is the auto-generated `__adb_auto_id__`, DTS cannot synchronize data from that table. During schema synchronization and full data synchronization, do not perform DDL operations that change the database or table schema. Otherwise, the data synchronization instance fails.
Other limitations	A data synchronization instance can synchronize only one table. To synchronize multiple tables, you must create multiple data synchronization instances. The destination database must contain a custom primary key. Or, in the Configurations for Databases, Tables, and Columns step, configure a Primary Key Column. Otherwise, synchronization may fail. Data verification is not supported. You cannot modify synchronization objects after the task is configured. If a data synchronization instance is suspended for more than one day, the binary log of the source AnalyticDB for MySQL 3.0 cluster may expire. As a result, the instance may not be recoverable. Do not disable the binary log for the source AnalyticDB for MySQL 3.0 cluster while the data synchronization instance is running. Otherwise, the instance fails and cannot be recovered. If an instance fails because the binary log was disabled, you must create a new instance to resolve the issue. If a node in the AnalyticDB for MySQL 3.0 cluster exceeds 80% disk space usage, the DTS instance may experience delays. We recommend that you estimate the required storage space based on the objects to be synchronized and ensure that the destination cluster has sufficient storage. If the destination AnalyticDB for MySQL 3.0 cluster is being backed up while the DTS instance is running, the instance fails. Initial full data synchronization involves concurrent INSERT operations, which can cause table fragmentation in the destination database. Consequently, after the initial full data synchronization, the tables in the destination database will occupy more storage space than those in the source instance. During initial full data synchronization, DTS consumes read and write resources from both the source and destination databases, which can increase database loads. We recommend that you assess the performance of your source and destination databases before you start and run the data synchronization during off-peak hours, such as when the CPU utilization for both databases is below 30%. When the destination database is an AnalyticDB for MySQL instance, DTS supports writing only the data types that are natively supported by the database. These include basic data types and complex data types such as ARRAY, MAP, and JSON. Other types, such as MULTIVALUE, are not supported. If a task fails, DTS support staff will attempt to restore it within eight hours. During restoration, they may restart the task or adjust its parameters. Note Only DTS task parameters are modified—not database parameters. Parameters that may be adjusted include those listed in Modify instance parameters.

Billing

Synchronization type	Pricing
Schema synchronization and full data synchronization	Free of charge.
Incremental data synchronization	Charged. For more information, see Billing overview.

Supported SQL operations

Operation type	SQL statement
DML	INSERT, UPDATE, DELETE Note When data is written to an AnalyticDB for MySQL 3.0 instance, UPDATE statements are automatically converted to REPLACE INTO statements. If the UPDATE statement targets the primary key, it is converted to DELETE+INSERT statements.
DDL	ADD COLUMN, DROP COLUMN

Account permissions

Database	Required permissions	Account setup
Source AnalyticDB for MySQL 3.0 cluster	Read permissions on the table to be synchronized.	Create a database account
Destination AnalyticDB for MySQL 3.0 cluster	Read and write permissions on the destination database.	Create a database account

Procedure

Go to the data synchronization task list page in the destination region. You can do this in one of two ways.
DTS console
1. Log on to the DTS console.
2. In the navigation pane on the left, click Data Synchronization.
3. In the upper-left corner of the page, select the region where the synchronization instance is located.
DMS console
Note
The 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.
1. Log on to the DMS console.
2. In the top menu bar, choose Data + AI > DTS (DTS) > Data Synchronization.
3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.
Click Create Task to open the task configuration page.

Configure the source and destination databases.

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	Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured. Note In 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 for MySQL 3.0.
	Access Method	Select Alibaba Cloud Instance.
	Instance Region	Select the region where the source AnalyticDB for MySQL 3.0 cluster resides.
	Replicate Data Across Alibaba Cloud Accounts	For this example, select No, as the database instance belongs to the current Alibaba Cloud account.
	Instance ID	Select the ID of the source AnalyticDB for MySQL 3.0 cluster.
	Database Account	Enter the database account for the source AnalyticDB for MySQL 3.0 cluster. For information about the required permissions, see Account permissions.
	Database Password	Enter the password for the specified database account.
Destination Database	Select Existing Connection	Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured. Note In 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 for MySQL 3.0.
	Access Method	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 information about the required permissions, see Account permissions.
	Database Password	Enter the password for the specified database account.

After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page.
Note
Ensure that the IP address blocks of the DTS service are added to the security settings of the source and destination databases, either automatically or manually, to allow access from DTS servers. For more information, see Add the IP address whitelist of DTS servers.

Configure the task objects.

On the Configure Objects page, specify the objects to synchronize.

Parameter	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.
DDL and DML Operations to Be Synchronized	Select the instance-level operations to synchronize during incremental data synchronization. Note To select table-level operations, right-click the synchronization object in the Selected Objects list and select the desired operations in the dialog box that appears.
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. Note If 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. Warning Selecting 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.
Source Objects	In the Source Objects box, select the table to synchronize and click to move it to the Selected Objects box. Important You can select only one table.
Selected Objects	To set the name of a synchronization object in the destination instance, right-click the object in the Selected Objects box to modify it. For more information, see Database Table Column Name Mapping. To remove a synchronization object, click it in the Selected Objects box, and then click to move it to the Source Objects box. Note If you use the object name mapping feature, other objects that depend on the mapped object may fail to synchronize. To set WHERE conditions to filter data for a table, right-click the table in the Selected Objects box and set the filter conditions in the dialog box that appears. For more information, see Set filter conditions. To select SQL operations for incremental synchronization, right-click the synchronization object in the Selected Objects box and select the desired operations from the dialog box.

Click Next: Advanced Settings.

Parameter	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. Note If 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. Important The 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). Note This 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	You can select an environment tag to identify the instance based on your needs. For this tutorial, no tag is required.
Configure ETL	Choose whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: Enables the ETL feature. Enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: Disables the ETL feature.
Monitoring and Alerting	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 contact. 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 the preceding configurations are complete, click Next: Configure Database and Table Fields to configure the Type, Primary Key Column, Distribution Key, and partition key information (Partition Key, Partitioning Rules, and Partition Lifecycle) for the tables to be synchronized in the destination database.
Note
- This step is available only if you select Schema Synchronization for the Synchronization Types parameter. You can set Definition Status to All to modify the fields.
- For the Primary Key Column, you can select multiple columns to form a composite primary key. 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.

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.
Note
- Before 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.

Purchase the data synchronization 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. Note This 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.