You can use Data Transmission Service (DTS) to synchronize data from a MongoDB database(replica set architecture) to another MongoDB database(replica set architecture or sharded cluster architecture).
Supported source and destination databases
The following table lists the types of source and destination MongoDB databases that are supported by DTS. In this example, the source database is an ApsaraDB for MongoDB instance (replica set architecture) and the destination database is an ApsaraDB for MongoDB instance (replica set architecture or sharded cluster architecture). You can also follow the procedure to configure data synchronization tasks for other types of MongoDB databases.Source database | Destination database |
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ApsaraDB for MongoDB instance (replica set architecture) | ApsaraDB for MongoDB instance (replica set architecture or sharded cluster architecture) |
Self-managed MongoDB database (replica set architecture) that is hosted on an Elastic Compute Service (ECS) instance | Self-managed MongoDB database (replica set architecture or sharded cluster architecture) that is hosted on an ECS instance |
Self-managed MongoDB database (replica set architecture) that is connected over Express Connect, VPN Gateway, or Smart Access Gateway | Self-managed MongoDB database (replica set architecture or sharded cluster architecture) that is connected over Express Connect, VPN Gateway, or Smart Access Gateway |
Prerequisites
- The source ApsaraDB for MongoDB instance (replica set architecture) and the destination ApsaraDB for MongoDB instance (replica set architecture or sharded cluster architecture) are created. For more information, see Create a replica set instance and Create a sharded cluster instance. Note For more information about the supported database versions, see Overview of data synchronization scenarios.
- The available storage space of the destination ApsaraDB for MongoDB instance is 10% larger than the total size of the data in the source ApsaraDB for MongoDB instance.
- Databases and collections to be sharded are created in the destination ApsaraDB for MongoDB instance and sharding is configured based on your business requirements if the destination ApsaraDB for MongoDB instance is deployed in the sharded cluster architecture. For more information, see Configure sharding to maximize the performance of shards. Note
- After you configure sharding for a sharded cluster instance, the synchronized data will be distributed among different shards. This maximizes the performance of the sharded cluster.
- The shard nodes in a sharded cluster instance must share the same account password and endpoint. For more information, see Apply for an endpoint for a shard or Configserver node.
Limits
Category | Description |
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Limits on the source database |
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Other limits |
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Special cases | If the source database is a self-managed MongoDB database, take note of the following limits:
Note If you select an entire database as the object to be synchronized, you can create a heartbeat. The heartbeat is updated or receives data every second. |
Billing
Synchronization type | Task configuration fee |
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Schema synchronization and full data synchronization | Free of charge. |
Incremental data synchronization | Charged. For more information, see Billing overview. |
Supported synchronization topologies
- One-way one-to-one synchronization
- One-way one-to-many synchronization
- One-way many-to-one synchronization
- One-way cascade synchronization
Synchronization types
Synchronization type | Description |
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Schema synchronization | DTS synchronizes the schemas of objects from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance. |
Full data synchronization | DTS synchronizes all existing data of objects from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance. Note DTS supports full data synchronization for the following types of objects: database, collection, and index. |
Incremental data synchronization | DTS synchronizes incremental data from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance. Note DTS does not support incremental data synchronization from databases that are created after the task starts to run. DTS synchronizes incremental data generated by the following operations:
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Procedure
- Go to the Data Synchronization Tasks page.
- Log on to the Data Management (DMS) console.
- In the top navigation bar, click DTS.
- In the left-side navigation pane, choose .
Note- Operations may vary based on the mode and layout of the DMS console. For more information, see Simple mode and Configure the DMS console based on your business requirements.
- You can also go to the Data Synchronization Tasks page of the new DTS console.
- From the drop-down list to the right of Data Synchronization Tasks, select the region in which the data synchronization instance resides. Note If you use the new DTS console, you must select the region in which the data synchronization instance resides in the top navigation bar.
- Click Create Task. On the page that appears, configure the source and destination databases.Warning After you select the source and destination instances, we recommend that you read the limits displayed in the upper part of the page. This helps you create and run the data synchronization task.
Section Parameter Description N/A Task Name DTS automatically generates a task name. We recommend that you specify an informative name to identify the task. You do not need to use a unique task name.
Source Database Select Instance Select whether to use an existing instance.- If you select an existing instance, DTS automatically applies the parameter settings of the instance. You do not need to configure the corresponding parameters again.
- If you do not use an existing instance, you must configure parameters for the source 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. Architecture The architecture in which the source instance is deployed. Select Replica Set. Instance ID The ID of the source ApsaraDB for MongoDB instance. Authentication Database The name of the authentication database to which the objects to be synchronized in the source ApsaraDB for MongoDB instance belong. 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. The account must have read permissions on the source, admin, and local databases. Database Password The password of the database account.
Destination Database Select Instance Select whether to use an existing instance.- If you select an existing instance, DTS automatically applies the parameter settings of the instance. You do not need to configure the corresponding parameters again.
- If you do not use an existing instance, you must configure parameters for the source database.
Database Type The type of the destination database. Select MongoDB. Access Method The access method of the destination database. Select Alibaba Cloud Instance. Instance Region The region in which the destination ApsaraDB for MongoDB instance resides. Architecture The architecture in which the destination ApsaraDB for MongoDB instance is deployed. Instance ID The ID of the destination ApsaraDB for MongoDB instance. Authentication Database The name of the authentication database to which the synchronized objects in the destination ApsaraDB for MongoDB instance belong. If you did not change the name before, the default value is admin. Database Account The database account of the destination ApsaraDB for MongoDB instance. The account must have the dbAdminAnyDatabase permission, read and write permissions on the destination database, and read permissions on the local database. Database Password The password of the database account.
- In the lower part of the page, click Test Connectivity and Proceed.
Warning
- If the source or destination database is an Alibaba Cloud database instance, such as an ApsaraDB RDS for MySQL or ApsaraDB for MongoDB, DTS automatically adds the CIDR blocks of DTS servers to the whitelist of the instance. For more information, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases. 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 need to manually add the CIDR blocks of DTS servers to the whitelist of the self-managed database on the ECS instance to allow DTS to access the database. 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.
- If the CIDR blocks of DTS servers are automatically or manually added to the whitelist or 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.
- After the DTS task is complete or released, we recommend that you manually remove the CIDR blocks of DTS servers from the whitelist or ECS security group rules. You must remove the IP address whitelist group whose name contains
dts
from the whitelist of the Alibaba Cloud database instance or the security group rules of the ECS instance. For more information about the CIDR blocks that you must remove from the whitelist of the self-managed databases that are deployed in data centers or databases that are hosted on third-party cloud services, see Add the CIDR blocks of DTS servers to the security settings of on-premises databases.
- Select objects for the task and configure advanced settings.
Parameter Description Task Stages By default, Incremental Data Synchronization is selected. You must also select Schema Synchronization and Full Data Synchronization. After the precheck is complete, DTS synchronizes the historical data of the selected objects from the source database to the destination database. The historical data is the basis for subsequent incremental synchronization.
Note For more information, see Synchronization types.Processing Mode of Conflicting Tables - Precheck and Report Errors: checks whether the destination database contains collections that have the same names as collections in the source database. If the source and destination databases do not contain collections that have identical collection names, the precheck is passed. Otherwise, an error is returned during the precheck, and the data synchronization task cannot be started.
Note You can use the object name mapping feature to rename the collections that are synchronized to the destination database. You can use this feature if the source and destination databases contain identical collection names and the collections in the destination database cannot be deleted or renamed. For more information, see Rename an object to be synchronized.
- Ignore Errors and Proceed: skips the precheck for identical collection names in the source and destination databases.
Warning If you select Ignore Errors and Proceed, data inconsistency may occur, and your business may be exposed to potential risks.
- DTS does not synchronize data records that have the same primary key values as data records in the destination database.
- Data may fail to be initialized, only some columns are synchronized, or the data synchronization task fails.
Synchronization Topology Select One-way Synchronization. Capitalization of Object Names in Destination Instance The capitalization of database names and collection names in the destination instance. By default, DTS default policy is selected. You can select other options to make sure that the capitalization of object names is consistent with that in the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.
Source Objects Select one or more objects from the Source Objects section and click the
icon to add the objects to the Selected Objects section.
Note You can select databases or collections as the objects to be synchronized.Selected Objects - To rename an object that you want to synchronize to the destination instance, right-click the object in the Selected Objects section. For more information, see Map the name of a single object.
- To rename multiple objects at a time, click Batch Edit in the upper-right corner of the Selected Objects section. For more information, see Map multiple object names at a time.
Note- To select the SQL operations performed on a specific database or table, right-click an object in the Selected Objects section. In the dialog box that appears, select the SQL operations that you want to synchronize. For more information about the SQL operations that can be synchronized, see Synchronization types.
- To specify WHERE conditions to filter data, right-click an object in the Selected Objects section. In the dialog box that appears, specify the conditions. For more information, see Use SQL conditions to filter data.
- Precheck and Report Errors: checks whether the destination database contains collections that have the same names as collections in the source database. If the source and destination databases do not contain collections that have identical collection names, the precheck is passed. Otherwise, an error is returned during the precheck, and the data synchronization task cannot be started.
- Click Next: Advanced Settings to configure advanced settings.
- Data Verification Settings
For more information about how to enable data verification, see Enable data verification.
- Advanced Settings
Parameter Description Set Alerts Specifies whether to set alerts for the data migration task. If the task fails or the migration latency exceeds the threshold, the alert contacts will receive notifications. Valid values:- No: does not set alerts.
- Yes: sets alerts. If you select Yes, you must also set the alert threshold and alert contacts. For more information, see Configure monitoring and alerting when you create a DTS task.
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 migration 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 the 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 migration task. Otherwise, the data migration task fails.Note- If you set different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is set later takes precedence.
- If DTS retries a connection, you are charged for the operation of the DTS instance. We recommend that you specify the retry time based on your business needs and release the DTS instance at your earliest opportunity after the source and destination instances are released.
Configure ETL Specifies whether to configure 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.
- Data Verification Settings
- In the lower part of the page, click Next: Save Task Settings and Precheck.
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 generated for an item during the precheck, perform the following operations based on the scenario:
- In scenarios where you cannot ignore the alert item, click View Details next to the failed item. After you analyze the causes based on the check results, troubleshoot the issues. Then, run a precheck again.
- In scenarios where you can ignore the alert item, click Confirm Alert Details next to the failed item. 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.
- Wait until the success rate becomes 100%. Then, click Next: Purchase Instance.
- 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 the instance 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 charged on an hourly basis. The pay-as-you-go billing method is suitable for short-term use. If you no longer require a pay-as-you-go instance, you can release the pay-as-you-go instance to reduce costs.
Instance Class DTS provides several instance classes that have different performance in synchronization speed. You can select an instance class based on your business scenario. For more information, see Specifications of data synchronization instances. Subscription 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 or one to three years. Note This parameter is displayed only if you select the subscription billing method. - Read and select the check box for Data Transmission Service (Pay-as-you-go) Service Terms.
- Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.