Data Transmission Service:Synchronize data from an ApsaraDB for MongoDB sharded cluster instance to a Function Compute function

Prerequisites

• The source ApsaraDB for MongoDB sharded cluster instance is created. For more information, see Create a sharded cluster instance.

• The destination service and the function are created and the Handler Type parameter is set to Event Handler for the function. For more information about how to create a function, see Quickly create a function.

Limits

Billing

Operations that support data synchronization

Permissions required for database accounts

Procedure

1. Go to the Data Synchronization Tasks page.

   1. Log on to the DMS console.

   2. In the top navigation bar, move the pointer over DTS.

   3. In the left-side navigation pane, choose DTS (DTS) > Data Synchronization.

   Note

   • The actual operation may vary depending on the mode and layout of DMS. For more information, see Simple mode and Customize the layout and style of the DMS console.

   • You can also go to the Data Synchronization Tasks page of the new DTS console.

2. On the right side of Data Synchronization Tasks, select the region in which you want to create the data synchronization task.

   Note

   If you use the new DTS console, select the region in which you want to create the data synchronization task in the upper-left corner of the page.

3. Click Create Task. In the Create Task wizard, configure the source and destination databases.

   Section	Parameter	Description
   N/A	Task Name	The name of the DTS task. DTS automatically generates a task name. We recommend that you specify a descriptive name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Select an existing DMS database instance. (Optional. If you have not registered a DMS database instance, ignore this option and configure database settings in the section below.)	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the source database. Select MongoDB.
   	Access Method	The access method of the source database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the source ApsaraDB for MongoDB instance resides.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether to synchronize data across Alibaba Cloud accounts. In this example, No is selected.
   	Architecture	The architecture in which the source instance is deployed. Select Sharded Cluster.
   	Instance ID	The ID of the source ApsaraDB for MongoDB instance.
   	Authentication Database	The name of the authentication database that stores database accounts and passwords of the source ApsaraDB for MongoDB instance. If you did not change the name before, the default value is admin.
   	Database Account	The database account of the source ApsaraDB for MongoDB instance. For more information about the required permissions, see the Permissions required for database accounts section of this topic.
   	Database Password	The password of the database account.
   	Shard Account	The account that is used to access the shards in the source ApsaraDB for MongoDB instance.
   	Shard Password	The password of the shard account of the source ApsaraDB for MongoDB instance.
   Destination Database	Select an existing DMS database instance. (Optional. If you have not registered a DMS database instance, ignore this option and configure database settings in the section below.)	Select whether to use an existing instance. If you select an existing instance, DTS automatically populates the parameters for the database. If you do not select an existing instance, you must manually configure parameters for the database.
   	Database Type	The type of the destination database. Select Function Compute.
   	Access Method	The access method of the destination database. Select Alibaba Cloud Instance.
   	Instance Region	The region in which the destination database resides. By default, the value is the same as that of the Instance Region parameter of the source database and cannot be changed.
   	Service	The name of the service to which the destination function belongs.
   	Function	The destination function that receives the synchronized data.
   	Service Version and Alias	The version or alias of the service. Configure this parameter based on your business requirements. If you select Default Version, the value of the Service Version parameter is fixed to LATEST. If you select Specified Version, you must configure the Service Version parameter. If you select Specified Alias, you must configure the Service Alias parameter. Note For more information about the terms of Function Compute, see Terms.

4. In the lower part of the page, click Test Connectivity and Proceed.

   If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB instance, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. If the source or destination database is a self-managed database hosted on an Elastic Compute Service (ECS) instance, DTS automatically adds the CIDR blocks of DTS servers to the security group rules of the ECS instance, and you must make sure that the ECS instance can access the database. If the database is deployed on multiple ECS instances, you must manually add the CIDR blocks of DTS servers to the security group rules of each ECS instance. If the source or destination database is a self-managed database that is deployed in a data center or provided by a third-party cloud service provider, you must manually add the CIDR blocks of DTS servers to the whitelist of the database to allow DTS to access the database. For more information, see Add the CIDR blocks of DTS servers.

   Warning

   If the CIDR blocks of DTS servers are automatically or manually added to the whitelist of the database or instance, or to the ECS security group rules, security risks may arise. Therefore, before you use DTS to synchronize data, you must understand and acknowledge the potential risks and take preventive measures, including but not limited to the following measures: enhancing the security of your username and password, limiting the ports that are exposed, authenticating API calls, regularly checking the whitelist or ECS security group rules and forbidding unauthorized CIDR blocks, or connecting the database to DTS by using Express Connect, VPN Gateway, or Smart Access Gateway.

5. Configure the objects to be synchronized and advanced settings.

   Parameter	Description
   Synchronization Types	By default, Incremental Data Synchronization is selected and you cannot change the value.
   Data Format	The format in which the synchronized data is stored in the destination function. Only the Canal Json format is supported. Note For more information about the parameters of the Canal JSON format, see the "Canal Json" section of the Data formats of a Kafka cluster topic.
   Source Objects	Select one or more objects from the Source Objects section and click the icon to move the objects to the Selected Objects section. Note You can select databases or collections as the objects to be synchronized.
   Selected Objects	In the Selected Objects section, check the data that you want to synchronize. Note To remove a selected object, select the objects that you want to remove in the Selected Objects section and click the icon.

6. Click Next: Advanced Settings to configure advanced settings.

   Parameter	Description
   Select the dedicated cluster used to schedule the task	By default, DTS schedules tasks to shared clusters. You do not need to configure this parameter. You can purchase a dedicated cluster of specific specifications to run DTS data synchronization tasks. For more information, see What is a DTS dedicated cluster.
   Set Alerts	Specifies whether to configure alerting for the data synchronization task. If the task fails or the synchronization latency exceeds the specified threshold, alert contacts will receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert contacts. For more information, see Configure monitoring and alerting.
   Retry Time for Failed Connections	The retry time range for failed connections. If the source or destination database fails to be connected after the data synchronization task is started, DTS immediately retries a connection within the time range. Valid values: 10 to 1440. Unit: minutes. Default value: 720. We recommend that you set this parameter to a value greater than 30. If DTS reconnects to the source and destination databases within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Note If you specify different retry time ranges for multiple data synchronization tasks that have the same source or destination database, the shortest retry time range takes precedence. When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time range based on your business requirements. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
   The wait time before a retry when other issues occur in the source and destination databases.	The retry time range for other issues. For example, if the DDL or DML operations fail to be performed after the data synchronization task is started, DTS immediately retries the operations within the time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set this parameter to a value greater than 10. If the failed operations are successfully performed within the specified time range, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails. Important The value of the The wait time before a retry when other issues occur in the source and destination databases. parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
   Enable Throttling for Incremental Data Synchronization	Specifies whether to enable throttling for incremental data synchronization. You can enable throttling for incremental data synchronization based on your business requirements. To configure throttling, you must configure the RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s) parameters. This reduces the load on the destination database server.
   Environment Tag	The environment tag that is used to identify the DTS instance. You can select an environment tag based on your business requirements. In this example, no environment tag is added.
   Configure ETL	Specifies whether to enable the extract, transform, and load (ETL) feature. For more information, see What is ETL? Valid values: Yes: configures the ETL feature. You can enter data processing statements in the code editor. For more information, see Configure ETL in a data migration or data synchronization task. No: does not configure the ETL feature.

7. Save the task settings and run a precheck.

   • To view the parameters to be specified when you call the relevant API operation to configure the DTS task, move the pointer over Next: Save Task Settings and Precheck and click Preview OpenAPI parameters.

   • If you do not need to view or have viewed the parameters, click Next: Save Task Settings and Precheck in the lower part of the page.

   Note

   • Before you can start the data synchronization task, DTS performs a precheck. You can start the data synchronization task only after the task passes the precheck.

   • If the task fails to pass the precheck, click View Details next to each failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.

   • If an alert is triggered for an item during the precheck:

     • If an alert item cannot be ignored, click View Details next to the failed item and troubleshoot the issue. Then, run a precheck again.

     • If an alert item can be ignored, click Confirm Alert Details. In the View Details dialog box, click Ignore. In the message that appears, click OK. Then, click Precheck Again to run a precheck again. If you ignore the alert item, data inconsistency may occur and your business may be exposed to potential risks.

8. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

9. On the Purchase Instance page, configure the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.

   Section	Parameter	Description
   New Instance Class	Billing Method	Subscription: You pay for your subscription when you create an instance. The subscription billing method is more cost-effective than the pay-as-you-go billing method for long-term use. Pay-as-you-go: A pay-as-you-go instance is billed on an hourly basis. We recommend that you select the pay-as-you-go billing method for short-term use. If you no longer require a pay-as-you-go instance, you can release the instance to reduce costs.
   	Resource Group	The resource group to which the instance belongs. Default value: default resource group. For more information, see What is Resource Management?
   	Instance Class	DTS provides various synchronization specifications that provide different performance. The synchronization speed varies based on the synchronization specifications that you select. You can select a synchronization specification based on your business requirements. For more information, see Specifications of data synchronization instances.
   	Duration	If you select the subscription billing method, set the subscription duration and the number of instances that you want to create. The subscription duration can be one to nine months, one year, two years, three years, or five years. Note This parameter is displayed only if you select the subscription billing method.Subscription

10. Read and select the Data Transmission Service (Pay-as-you-go) Service Terms.

11. Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.

12. Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.

Formats of data received by the destination function

The data received by the destination function is of the Object type. Incremental data of the source database is stored in the Records field in the array format. Each element in the array indicates a data record of the Object type. The following table describes the fields in the data records of the Object type.

db.createCollection("testCollection")

{
	'Records': [{
		'data': [{
			'doc': '{"create": "testCollection", "idIndex": {"v": 2, "key": {"_id": 1}, "name": "_id_"}}'
		}],
		'pkNames': ['_id'],
		'type': 'DDL',
		'es': 1694056437000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': True,
		'table': 'testCollection',
		'ts': 1694056437510
	}]
}

db.testCollection.drop()

{
	'Records': [{
		'data': [{
			'doc': '{"drop": "testCollection"}'
		}],
		'pkNames': ['_id'],
		'type': 'DDL',
		'es': 1694056577000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': True,
		'table': 'testCollection',
		'ts': 1694056577789
	}]
}

db.testCollection.createIndex({name:1})

{
	'Records': [{
		'data': [{
			'doc': '{"createIndexes": "testCollection", "v": 2, "key": {"name": 1}, "name": "name_1"}'
		}],
		'pkNames': ['_id'],
		'type': 'DDL',
		'es': 1694056670000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': True,
		'table': 'testCollection',
		'ts': 1694056670719
	}]
}

db.testCollection.dropIndex({name:1})

{
	'Records': [{
		'data': [{
			'doc': '{"dropIndexes": "testCollection", "index": "name_1"}'
		}],
		'pkNames': ['_id'],
		'type': 'DDL',
		'es': 1694056817000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': True,
		'table': '$cmd',
		'ts': 1694056818035
	}]
}

// Insert multiple data records at a time.
db.runCommand({insert: "user", documents: [{"name":"jack","age":20},{"name":"lili","age":20}]})

// Insert one data record at a time.
db.user.insert({"name":"jack","age":20})
db.user.insert({"name":"lili","age":20})

{
	'Records': [{
		'data': [{
			'doc': '{"_id": {"$oid": "64f9397f6e255f74d65a****"}, "name": "jack", "age": 20}'
		}],
		'pkNames': ['_id'],
		'type': 'INSERT',
		'es': 1694054783000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': False,
		'table': 'user',
		'ts': 1694054784427
	}, {
		'data': [{
			'doc': '{"_id": {"$oid": "64f9397f6e255f74d65a****"}, "name": "lili", "age": 20}'
		}],
		'pkNames': ['_id'],
		'type': 'INSERT',
		'es': 1694054783000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': False,
		'table': 'user',
		'ts': 1694054784428
	}]
}

db.user.update({"name":"jack"},{$set:{"age":30}}) 

{
	'Records': [{
		'data': [{
			'doc': '{"$set": {"age": 30}}'
		}],
		'pkNames': ['_id'],
		'old': [{
			'doc': '{"_id": {"$oid": "64f9397f6e255f74d65a****"}}'
		}],
		'type': 'UPDATE',
		'es': 1694054989000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': False,
		'table': 'user',
		'ts': 1694054990555
	}]
}

db.user.remove({"name":"jack"})

{
	'Records': [{
		'data': [{
			'doc': '{"_id": {"$oid": "64f9397f6e255f74d65a****"}}'
		}],
		'pkNames': ['_id'],
		'type': 'DELETE',
		'es': 1694055452000,
		'database': 'MongoDBTest',
		'id': 0,
		'isDdl': False,
		'table': 'user',
		'ts': 1694055452852
	}]
}