Data Transmission Service:Migrate from MongoDB to AnalyticDB for MySQL V3.0

Prerequisites

• If the source is an ApsaraDB for MongoDB sharded cluster, apply for an endpoint for each shard. The username and password for all shards must be identical. For more information, see Apply for a shard endpoint.

• You have a destination AnalyticDB for MySQL 3.0 cluster whose storage space is larger than the used storage space of the source ApsaraDB for MongoDB instance. For more information, see Create a cluster.

  Note

  The storage space of the destination instance should be at least 10% larger than the used storage space of the source instance.

• In the destination AnalyticDB for MySQL 3.0 cluster, you have a database and a table with a primary key. For more information, see CREATE DATABASE and CREATE TABLE.

  Important

  • The data types in the destination table must be compatible with the data in the source MongoDB instance. For example, if the _id field in MongoDB is of the ObjectId type, the corresponding data type in the AnalyticDB for MySQL 3.0 cluster must be varchar.

  • In an AnalyticDB for MySQL 3.0 cluster, do not name columns in the destination table _id or _value.

• Run the SET ADB_CONFIG ALLOW_MULTI_QUERIES=true; command in the destination AnalyticDB for MySQL 3.0 cluster to enable the Multi-Statement feature.

  Note

  Only clusters with minor version 3.1.9.3 or later support the Multi-Statement feature. To view and upgrade the minor version, see Upgrade minor version.

Usage notes

Billing

Migration types

Database account permissions

Procedure

1. Navigate to the migration task list page for the destination region using one of the following methods.

   From the DTS console

   1. Log on to the Data Transmission Service (DTS) console.

   2. In the navigation pane on the left, click Data Migration.

   3. In the upper-left corner of the page, select the region where the migration instance is located.

   From the DMS console

   Note

   The actual operations may vary based 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 Data Management (DMS) console.

   2. In the top menu bar, choose Data + AI > Data Transmission (DTS) > Data Migration.

   3. To the right of Data Migration Tasks, select the region where the migration instance is located.

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

3. 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	To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured. Note In the DMS console, this parameter is named Select a DMS database instance.. If you have not registered the database instance with the system, or do not need to use a registered instance, manually configure the database information below.
   	Database Type	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	In this example, a database instance under the current Alibaba Cloud account is used. Select No.
   	Architecture	This example selects Replica Set. Note If your source ApsaraDB for MongoDB instance uses the Sharded Cluster, you must also specify Shard account and Shard password.
   	Migration Method	Select a method for incremental data migration based on your requirements. Oplog (Recommended): This option is available if an oplog is enabled for the source database. Note An oplog is enabled by default for both self-managed MongoDB databases and ApsaraDB for MongoDB instances. This method offers lower latency for incremental data migration due to faster log pulling. Therefore, 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 instance (non-elastic cluster), you can only select ChangeStream. If you set Architecture to Sharded Cluster for the source database, you do not need to enter a Shard account or Shard password.
   	Instance ID	Select the instance ID of the source ApsaraDB for MongoDB instance.
   	Authentication Database	Enter the name of the database to which the database account of the source ApsaraDB for MongoDB instance belongs. The default value is admin if it has not been changed.
   	Database Account	Enter the database account of the source ApsaraDB for MongoDB instance. For information about the required permissions, see Permissions required 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	To use a database instance that has been added to the system (created or saved), select the desired database instance from the drop-down list. The database information below will be automatically configured. Note In the DMS console, this parameter is named Select a DMS database instance.. If you have not registered the database instance with the system, 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 of the destination AnalyticDB for MySQL 3.0 cluster.
   	Instance ID	Select the ID of the destination AnalyticDB for MySQL 3.0 cluster.
   	Database Account	Enter the database account of the destination AnalyticDB for MySQL 3.0 cluster. For information about the required permissions, see Permissions required for database accounts.
   	Database Password	Enter the password for the specified database account.

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

   Note

   • Ensure that the IP address segment of the DTS service is automatically or manually added to the security settings of the source and destination databases to allow access from DTS servers. For more information, see Add DTS server IP addresses to a whitelist.

   • If the source or destination database is a self-managed database (the Access Method is not Alibaba Cloud Instance), you must also click Test Connectivity in the CIDR Blocks of DTS Servers dialog box that appears.

5. Configure the task objects.

   1. On the Configure Objects page, configure the objects that you want to migrate.

      Parameter	Description
      Migration Types	If you only need to perform a full migration, select Full Data Migration. To perform a migration with no downtime, select both Full Data Migration and Incremental Data Migration. Note If you do not select Incremental Data Migration, do not write new data to the source instance during data migration to ensure data consistency.
      DDL and DML Operations to Be Synchronized	Select the operations to be migrated at the instance level during incremental migration. Note To select incremental operations at the collection level, right-click the migration object in the Selected Objects section and select the desired operations in the dialog box that appears.
      Merge Tables	If you select Yes, DTS adds the __dts_data_source column to each table to record data sources. For more information, see Enable multi-table merge. If you select No, this is the default option. Note The table merging feature is configured at the task level, not the table level. To merge some tables but not others, you must create two separate data migration tasks. Warning Do not perform DDL operations to change the schema of the source database or tables. Otherwise, data inconsistency or task failure may occur.
      Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks whether collections with the same names exist in the destination database. If no collections with the same names exist, the precheck is passed. If collections with the same names exist, an error is reported during the precheck, and the data migration task does not start. Note If a collection in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the collection in the destination database. For more information, see Object name mapping. Ignore Errors and Proceed: Skips the check for collections with the same names. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. For example: If a record in the destination database has the same primary key value as a record in the source database, the record in the destination database is kept. The record from the source database is not migrated to the destination database. Data initialization may fail, only some data may be migrated, or the migration may fail.
      Source Objects	In the Source Objects box, click the objects to migrate, and then click to move them to the Selected Objects box. Note Migration objects can be selected at the collection level.
      Selected Objects	Edit the database name mapping. In the Selected Objects box, right-click the database that contains the collections to be migrated. Change the Schema Name to the name of the destination database in the AnalyticDB for MySQL 3.0 cluster. In the Edit Schema dialog box that appears, modify the Schema Name (for example, to dtsdb). Optional: In the Select DDL and DML Operations to Be Synchronized section, select the DML operations to migrate, such as insert, update, and delete. Click OK. Edit the table name mapping. In the Selected Objects box, right-click the collection to be migrated. The Selected Objects panel displays a tree structure of objects in the database (such as dtsdb), including object types (such as Table) and specific objects (such as class). Change the Table Name to the name of the destination table in the AnalyticDB for MySQL 3.0 cluster. In the Edit Table page that appears, you can modify the Table Name (which is class in this example). After editing the table or column name, the names in the destination database are changed accordingly. Optional: Set filter conditions for the full migration. For more information, see Set filter conditions. For ApsaraDB for MongoDB, the supported syntax for filter conditions is different from standard SQL WHERE clauses. For example, to filter by user ID, enter the following condition: {"_id": {$gt:"user100844658590795****",$lte:"user101674868045948****"}}, where $gt means greater than and $lte means less than or equal to. Optional: In the Select DDL and DML Operations to Be Synchronized section, select the DML operations to migrate, such as insert, update, and delete. Configure the MongoDB fields to migrate. By default, DTS maps the data of the collections to be migrated and configures an expression in the Parameter Value column. You must check whether the expression meets your requirements and configure parameters such as Column Name, Type, Length, and Precision. Important The primary key column of the destination table must be assigned the value bson_value("_id"). When you configure the bson_value() expression, you must specify the hierarchy down to the lowest-level subfield. Otherwise, data loss or task failure may occur. In the Parameter Value column, view the MongoDB field name in the bson_value() expression. The content inside the quotation marks ("") is the field name in MongoDB. For example, if the expression is bson_value("age"), this row corresponds to the age field in MongoDB. Optional: Delete fields that you do not need to migrate. Note To delete a field that you do not need to migrate, click the icon in the row of the field. Configure the fields to be migrated. Perform the subsequent operations based on whether the bson_value() expression meets your requirements. Matching expressions Enter a Column Name. Note Enter the name of the column in the destination table that will receive data in the AnalyticDB for MySQL 3.0 cluster. Select the data Type for the column. Important Make sure that the data type of the destination table is compatible with the source MongoDB data. For information about data type mappings, see Data type mappings. Optional: Configure the Length and Precision for the column data. Repeat these steps to map all relevant fields. Non-matching expressions Note An example is a field with a hierarchical (parent-child) structure. In the Operation column, click the icon in the row for the field. Click + Add Column. Configure the Column Name, Type, Length, and Precision. In the text box under Parameter Value, enter a bson_value() expression. For more information, see Assignment configuration examples. Repeat these steps to map all relevant fields. Click OK.

   2. Click Next: Advanced Settings to configure advanced parameters.

      Parameter	Description
      Dedicated Cluster for Task Scheduling	By default, DTS schedules tasks on a shared cluster. You do not need to select one. If you want more stable tasks, you can purchase a dedicated cluster to run DTS migration tasks.
      Retry Time for Failed Connections	After the migration task starts, if the connection to the source or destination database fails, 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 1440 minutes. We recommend that you set the duration to more than 30 minutes. If DTS reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails. Note For multiple DTS instances that share the same source or destination, the network retry time is determined by the setting of the last created task. Because you are charged for the task during the connection retry period, we recommend that you customize the retry time based on your business needs, or release the DTS instance as soon as possible after the source and destination database instances are released.
      Retry Time for Other Issues	After the migration task starts, if a non-connectivity issue, such as a DDL or DML execution exception, occurs in the source or destination database, DTS reports an error and immediately begins to retry the operation. The default retry duration is 10 minutes. You can customize the retry time to a value from 1 to 1440 minutes. We recommend that you set the duration to more than 10 minutes. If the related operations succeed within the specified retry duration, the migration task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than the value of Retry Time for Failed Connections.
      Enable Throttling for Full Data Migration	During full migration, DTS consumes read and write resources on the source and destination databases, which may increase the database load. If required, you can enable throttling for the full migration task. You can set Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Full Data Migration for Migration Types. You can also adjust the full migration speed after the migration instance is running.
      Only one data type for primary key _id in a table of the data to be synchronized	In the data to be migrated, is the data type of the primary key _id uniform within a single collection? Important Select an option based on your requirements. Otherwise, data loss may occur. This parameter is available only if you select Full Data Migration for Migration Types. Yes: The data type is unique. During full data migration, DTS does not scan the data types of primary keys in the source data. For a single collection, DTS migrates only the data corresponding to one primary key data type. No: The data type is not unique. During full data migration, DTS scans the data types of primary keys in the source data and migrates all data.
      Enable Throttling for Incremental Data Migration	If required, you can also choose to set speed limits for the incremental migration task. You can set RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) to reduce the load on the destination database. Note This configuration item is available only if you select Incremental Data Migration for Migration Types. You can also adjust the incremental migration speed after the migration instance is running.
      Environment Tag	You can select an environment tag to identify the instance. This is not required in this example.
      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	Select whether to set alerts and receive alert notifications based on your business needs. No: Does not set an alert. Yes: Configure alerts by setting an alert threshold and an alert notifications. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

6. Save the task and run a precheck.

   • To view the parameters for configuring this instance when you call the API operation, move the pointer over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the bubble that appears.

   • If you do not need to view or have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

   Note

   • Before the migration task starts, DTS performs a precheck. The task starts only after it passes the precheck.

   • If the precheck fails, click View Details next to the failed check item, fix the issue based on the prompt, and then run the precheck again.

   • If a warning is reported during the precheck:

     • For check items that cannot be ignored, click View Details next to the failed item, fix the issue based on the prompt, and then run the precheck again.

     • For check items that can be ignored, you can click Confirm Alert Details, Ignore, OK, and Precheck Again to skip the alert item and run the precheck again. If you choose to ignore a warning, it may cause issues such as data inconsistency and pose risks to your business.

7. Purchase the instance.

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

   2. On the Purchase page, select the link specification for the data migration instance. For more information, see the following table.

      Category	Parameter	Description
      New Instance Class	Resource Group Settings	Select the resource group to which the instance belongs. The default value is default resource group. For more information, see What is Resource Management?
      	Instance Class	DTS provides migration specifications with different performance levels. The link specification affects the migration speed. You can select a specification based on your business scenario. For more information, see Data migration link specifications.

   3. After the configuration is complete, read and select Data Transmission Service (Pay-as-you-go) Service Terms.

   4. Click Buy and Start. In the OK dialog box that appears, click OK.

      You can view the progress of the migration task on the Data Migration Tasks list page.

      Note

      • If the migration task does not include incremental migration, it stops automatically after the full migration is complete. After the task stops, its Status changes to Completed.

      • If the migration task includes incremental migration, it does not stop automatically. The incremental migration task continues to run. While the incremental migration task is running, the Status of the task is Running.

Data type mapping

Mapping configuration

{
  "_id":"62cd344c85c1ea6a2a9f****",
  "person":{
    "name":"neo",
    "age":26,
    "sex":"male"
  }
}