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

Prerequisites

• You have created the source ApsaraDB for MongoDB replica set instance. For more information, see Create a replica set instance.

• You have created the destination service and function, and set its Handler Type to Event Handler. To create a function, see Quickly create a function.

  Note

  Only Function Compute (FC) 2.0 is supported.

Usage notes

Billing

Supported synchronization operations

Permissions required for database accounts

Procedure

1. 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 DMS console layout and style.

   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.

2. Click Create Task to open the task configuration page.

3. Configure the source and destination databases.

   Category	Configuration	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	The type of the source database. Select MongoDB.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	Select the region of the source ApsaraDB for MongoDB instance.
   	Replicate Data Across Alibaba Cloud Accounts	Specifies whether data is synchronized across Alibaba Cloud accounts. In this example, select No.
   	Architecture	Select Replica Set.
   	Migration Method	Select a method for incremental data synchronization based on your requirements. Oplog (Recommended): This option is available if Oplog is enabled for the source database. Note Oplog is enabled by default for self-managed MongoDB databases and ApsaraDB for MongoDB instances. This method offers lower latency for incremental synchronization tasks because logs are retrieved faster. We recommend selecting Oplog. ChangeStream: This option is available if Change Streams are enabled for the source database. Note If the source database is an Amazon DocumentDB (non-elastic cluster) instance, you can select only ChangeStream. If you set Architecture of the source database to Sharded Cluster, you do not need to specify Shard account and Shard password.
   	Instance ID	Select the source ApsaraDB for MongoDB instance ID.
   	Authentication Database	Enter the name of the authentication database for the source ApsaraDB for MongoDB instance account. The default name is admin.
   	Database Account	Enter the database account for the source ApsaraDB for MongoDB instance. For permission requirements, see Permission requirements for database accounts.
   	Database Password	Enter the password for the specified database account.
   	Encryption	DTS supports three connection methods: Non-encrypted, SSL-encrypted, and Mongo Atlas SSL. The options for Encryption vary based on the selected Access Method and Architecture. The options displayed in the console prevail. Note A MongoDB database where the Architecture is Sharded Cluster and the Migration Method is Oplog does not support SSL-encrypted. If the source is a self-managed MongoDB database (Access Method is not Alibaba Cloud Instance) with a Replica Set architecture, and you select SSL-encrypted, DTS also allows you to upload a CA certificate to verify the connection.
   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 Function Compute.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	By default, the value is the same as the Instance Region of the source database and cannot be changed.
   	Service	The name of the target Function Compute service.
   	Function	The destination function in Function Compute (FC) that accepts the data.
   	Service Version and Alias	Select an option as needed. Default Version: The Service Version is fixed to LATEST. Specified Version: Select the Service Version. Specified Alias: Select the Service Alias. Note For more information about the terms of Function Compute, see Terms.

4. After completing the configuration, click Test Connectivity and Proceed at the bottom of the page.

   Note

   • Ensure 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.

5. Configure the task objects.

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

      Configuration	Description
      Synchronization Types	Only Incremental Data Synchronization is supported, and it is selected by default.
      Data Format	The storage format of data synchronized to the FC function. Only Canal Json is supported. Note For parameter descriptions and examples of the Canal Json format, see Canal Json description.
      Source Objects	In the Source Objects box, click the objects, and then click to move them to the Selected Objects box. Note You can select objects at the database or collection level.
      Selected Objects	In the Selected Objects box, confirm the data to sync. Note To remove objects, select them in the Selected Objects box and click . To filter incremental update operations by database or collection, right-click an object in the Selected Objects box and select the operations in the dialog box that appears.

   2. Click Next: Advanced Settings.

      Configuration	Note
      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.
      Obtain the entire document after it is updated.	During incremental data synchronization, specifies whether to synchronize the complete data of the document that corresponds to an update operation to the destination. Note This configuration item is available only when Migration Method is set to ChangeStream. Yes: Synchronizes the full data of the document that contains the updated field. Important This feature is based on the native capabilities of MongoDB and may increase the load on the source database. This can reduce the speed of incremental data collection and cause latency in the synchronization instance. If DTS fails to obtain the complete data, only the data of the updated field is synchronized. No: Synchronizes only the data of the updated fields.
      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	If needed, select an environment tag to identify the instance. For this example, no selection 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 notifications. For more information, see Configure monitoring and alerting during task configuration.

6. 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.

7. Purchase an instance.

   1. When the Success Rate reaches 100%, click Next: Purchase Instance.

   2. 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.

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

   4. Click Buy and Start, and then click OK in the OK dialog box.

      You can monitor the task progress on the data synchronization page.

What to do next

• If a DTS task fails because a single data record to be synchronized exceeds 16 MB, you can modify the sync objects or use the ETL feature to filter out large object data. For more information, see Modify the ETL configuration of an existing sync task and Modify sync objects.

• Write function code as needed. For more information, see Code Development Overview.

Formats of data received by the destination service

The data that FC receives is of the Object type. Incremental data from the source database is stored in the Records field as an array. Each element in the array is a data record of the Object type. The following table describes the fields of the Object.

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
	}]
}

// Bulk insert
db.runCommand({insert: "user", documents: [{"name":"jack","age":20},{"name":"lili","age":20}]})

// Insert one by one
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
	}]
}