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
ApsaraDB for MongoDB instance (replica set architecture) ApsaraDB for MongoDB instance (replica set architecture or sharded cluster architecture)
Self-managed MongoDB database that is hosted on ECS (replica set architecture) Self-managed MongoDB database (replica set architecture or sharded cluster architecture)
Self-managed MongoDB database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway (replica set architecture) Self-managed MongoDB database that is connected over Express Connect, VPN Gateway, or Smart Access Gateway (replica set architecture or sharded cluster architecture)

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 supported MongoDB versions, see Overview of data synchronization scenarios.
  • The available storage space of the destination ApsaraDB for MongoDB instance is larger than the total size of the data in the source ApsaraDB for MongoDB instance.
  • If the destination ApsaraDB for MongoDB instance is deployed in a sharded cluster architecture, you must create databases and collections to be sharded in the destination ApsaraDB for MongoDB instance and configure sharding based on your business needs. For more information, see Configure sharding to maximize the performance of shards.
    Note
    • After you configure sharding for a cluster, 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

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
For more information, see Synchronization topologies.

Synchronization types

Synchronization type Description
Schema synchronization DTS synchronizes the schemas of the required objects from the source ApsaraDB for MongoDB instance to the destination ApsaraDB for MongoDB instance.
Full data synchronization DTS synchronizes historical data of the required 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 supports the following types of incremental updates:
  • CREATE DATABASE, CREATE COLLECTION, and CREATE INDEX
  • DROP DATABASE, DROP COLLECTION, and DROP INDEX
  • RENAME COLLECTION

Procedure

  1. Go to the Data Synchronization page of the new DTS console.
    Note You can also log on to the Data Management (DMS) console. In the top navigation bar, choose DTS > Data Synchronization.
  2. In the upper-left corner of the page, select the region where the data synchronization instance resides.
    Select a region
  3. 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 at the top of the page. This helps you create and run the data synchronization task.
    MongoDB: Configure the source and destination databases
    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 Template
    If the connection settings of the instance has been saved as a template, you can select the connection name. DTS automatically applies the saved connection settings.
    Note
    • You can modify the connection settings of a template.
    • To edit the template name, you can click Edit Template Name at the bottom of the Source Database section.
    • The modified connection template will take effect the next time you select the connection template. The database instance that you have configured by using the template is not affected.
    Database Type Select MongoDB.
    Access Method Select Alibaba Cloud Instance.
    Instance Region Select the region where the source ApsaraDB for MongoDB instance resides.
    Instance ID Select the ID of the source ApsaraDB for MongoDB instance.
    Database Name Enter admin.
    Note Enter the name of the authentication database. The database account is created in this database.
    Database Account Enter the database account of the source ApsaraDB for MongoDB instance. The account must have the read permissions on the source database, admin database, and local database.
    Database Password

    Enter the password of the database account.

    Save as Template
    Click Save as Template. In the dialog box that appears, set the name of the database connection, and click OK. The connection settings of the database instance is saved as a template.
    Note We recommend that you specify an informative name to identify the database connection. You do not need to use a unique name.
    Destination Database Select Template
    If the connection settings of the instance has been saved as a template, you can select the connection name. DTS automatically applies the saved connection settings.
    Note
    • You can modify the connection settings of a template.
    • To edit the template name, you can click Edit Template Name at the bottom of the Source Database section.
    • The modified connection template will take effect the next time you select the connection template. The database instance that you have configured by using the template is not affected.
    Database Type Select MongoDB.
    Access Method Select Alibaba Cloud Instance.
    Instance Region Select the region where the destination ApsaraDB for MongoDB instance resides.
    Instance ID Select the ID of the destination ApsaraDB for MongoDB instance.
    Database Name Enter admin.
    Note Enter the name of the authentication database. The database account is created in this database.
    Database Account Enter the database account of the destination ApsaraDB for MongoDB instance. The account must have the dbAdminAnyDatabase permission, the read and write permissions on the destination database, and the read permissions on the local database.
    Database Password

    Enter the password of the database account.

    Save as Template
    Click Save as Template. In the dialog box that appears, set the name of the database connection, and click OK. The connection settings of the database instance is saved as a template.
    Note We recommend that you specify an informative name to identify the database connection. You do not need to use a unique name.
  4. In the lower part of the page, click Test Connectivity and Proceed.
  5. Select objects for the task and configure advanced settings.
    • Basic SettingsMongoDB: Basic Settings
      Parameter Description
      Task Stages

      Incremental Data Synchronization is selected by default. You must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS synchronizes the historical data of the selected objects from the source instance to the destination cluster. 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 identical collection names, the precheck is passed. Otherwise, an error is returned during 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 consistency is not guaranteed and your business may be exposed to potential risks.
        • DTS does not synchronize data records that have the same primary keys as data records in the destination database.
        • Data may fail to be initialized, only some columns are synchronized, or the data synchronization task fails.
      Select Objects

      Select one or more objects from the Source Objects section and click the Rightwards arrow icon to move the objects to the Selected Objects section.

      Note You can select databases or collections as the objects to be synchronized.
      Rename Databases and Tables
      • 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.
      Filter data

      You can specify WHERE conditions to filter data. For more information, see Use SQL conditions to filter data.

      Select the SQL operations to be synchronized In the Selected Objects section, right-click an object. In the dialog box that appears, select the SQL operations that you want to synchronize. For more information, see
    • Advanced SettingsMongoDB: Advanced Settings
      Parameter Description
      Set Alerts
      Specify whether to set alerts for the data synchronization task. If the task fails or the synchronization latency exceeds the threshold, the alert contacts will receive notifications.
      • Select No if you do not want to set alerts.
      • Select Yes to set alerts. In this case, you must also set the alert threshold and alert contacts.
      Capitalization of Object Names in Destination Instance

      Specify 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 of the source or destination database. For more information, see Specify the capitalization of object names in the destination instance.

      Retry Time for Failed Connection
      Specify the retry time for failed connections. Valid values: 10 to 1440. Unit: minutes. Default value: 120. We recommend that you set the retry time to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified time, DTS resumes the data synchronization task. Otherwise, the data synchronization task fails.
      Note
      • If multiple DTS instances have the same source or destination database, the lowest value takes effect. For example, the retry time is set to 30 minutes for Instance A and 60 minutes for Instance B, DTS retries failed connections at an interval of 30 minutes.
      • When DTS retries a connection, you are charged for the DTS instance. We recommend that you specify the retry time based on your business needs. You can also release the DTS instance at your earliest opportunity after the source and destination instances are released.
  6. 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, you can click the Info icon icon next to each failed item to view details.
      • You can troubleshoot the issues based on the causes and run a precheck again.
      • If you do not need to troubleshoot the issues, you can ignore failed items and run a precheck again.
  7. Wait until the Success Rate becomes 100%. Then, click Next: Purchase Instance.
  8. On the Purchase Instance page, specify the Billing Method and Instance Class parameters for the data synchronization instance. The following table describes the parameters.
    Section Parameter Description
    Parameters Billing Method
    • Subscription: You can pay for your subscription when you create an instance. We recommend that you select the subscription billing method for long-term use because it is more cost-effective than the pay-as-you-go billing method. You can save more costs with longer subscription periods.
    • 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 your pay-as-you-go instance, you can release it 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 Length If you select the subscription billing method, set the subscription length and the number of instances that you want to create. The subscription length can be one to nine months or one to three years.
    Note This parameter is available only if you select the subscription billing method.
  9. Read and select Data Transmission Service (Pay-as-you-go) Service Terms.
  10. Click Buy and Start to start the data synchronization task. You can view the progress of the task in the task list.