Data Transmission Service:Migrate data from PolarDB for MySQL to Elasticsearch

Prerequisites

• Create a destination Elasticsearch instance. For more information, see Beginner's guide: From instance creation to data retrieval.

• The destination Elasticsearch instance must have more storage space than the source PolarDB for MySQL instance.

Notes

Billing

Migration type descriptions

• Schema migration

  DTS migrates the schemas of the selected objects from the source database to the destination database.

• Full data migration

  DTS migrates the historical data of required objects from the source database to the destination database.

• Incremental data migration

  After full data migration is complete, DTS migrates incremental data from the source database to the destination database. Incremental data migration allows data to be migrated smoothly without interrupting the services of self-managed applications during data migration.

SQL operations supported for incremental migration

Database account permissions

Procedure

1. Use one of the following methods to go to the Data Migration page and select the region in which the data migration instance resides.

   DTS console

   1. Log on to the DTS console.

   2. In the left-side navigation pane, click Data Migration.

   3. In the upper-left corner of the page, select the region in which the data migration instance resides.

   DMS console

   Note

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

   1. Log on to the DMS console.

   2. In the top navigation bar, move the pointer over Data + AI > DTS (DTS) > Data Migration.

   3. From the drop-down list to the right of Data Migration Tasks, select the region in which the data synchronization instance resides.

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

3. Configure the source and destination databases. The following table describes the parameters.

   Section	Configuration	Description
   N/A	Task Name	The name of the DTS task. DTS automatically generates a task name. We recommend that you specify an informative name that makes it easy to identify the task. You do not need to specify a unique task name.
   Source Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
   	Database Type	Select PolarDB for MySQL.
   	Access Method	Select Cloud Instance.
   	Instance Region	Select the region where the source PolarDB for MySQL instance resides.
   	Replicate Data Across Alibaba Cloud Accounts	This example migrates data within the same Alibaba Cloud account. Select No.
   	PolarDB Instance ID	Select the ID of the source PolarDB for MySQL instance.
   	Database Account	Enter the database account of the source PolarDB for MySQL instance. For information about the required permissions, see Database account permissions.
   	Database Password	The password that is used to access the database instance.
   	Encryption	Specifies whether to encrypt the connection to the source database. You can configure this parameter based on your business requirements. For more information about the SSL encryption feature, see Configure SSL encryption.
   Destination Database	Select Existing Connection	If you use a database instance that is registered with DTS, select the instance from the drop-down list. DTS automatically populates the following database parameters for the instance. For more information, see Manage database connections. Note In the DMS console, you can select the database instance from the Select a DMS database instance drop-down list. If you fail to register the instance with DTS, or you do not need to use the instance that is registered with DTS, you must configure the following database information.
   	Database Type	Select Elasticsearch.
   	Access Method	Select Cloud Instance.
   	Instance Region	Select the region where the destination Elasticsearch instance resides.
   	Type	Select Cluster or Serverless as needed.
   	Instance ID	Select the ID of the destination Elasticsearch instance.
   	Database Account	Enter the database account for the Elasticsearch instance. The default account is elastic.
   	Database Password	Enter the logon password that you set when you created the Elasticsearch instance.
   	Encryption	Select HTTP or HTTPS as needed.

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

   Note

   • Make sure that the CIDR blocks of DTS servers can be 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 and its Access Method is not set to Alibaba Cloud Instance, click Test Connectivity in the CIDR Blocks of DTS Servers dialog box.

5. Configure the objects to be migrated.

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

      Configuration	Description
      Migration Types	To perform only full data migration, select Schema Migration and Full Data Migration. To ensure service continuity during data migration, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Schema Migration, make sure a database and a table are created in the destination database to receive data and the object name mapping feature is enabled in Selected Objects. If you do not select Incremental Data Migration, we recommend that you do not write data to the source database during data migration. This ensures data consistency between the source and destination databases.
      Processing Mode of Conflicting Tables	Precheck And Report Error: Checks whether the destination database contains tables that have the same names as tables in the source database. If no tables with the same name exist, the precheck passes. If tables with the same name exist, an error is reported during the precheck, and the migration task does not start. Note If you cannot delete or rename the tables with the same name in the destination database, you can map them to different names. For more information, see Map table and column names. Ignore Error And Continue: Skips the check for tables with the same name in the destination database. Warning If you select Ignore Error And Continue, data inconsistency may occur, which poses risks to your business. For example: If the table schemas are consistent and a record in the destination database has the same primary key value as a record in the source database: During full migration, DTS keeps the record in the destination cluster. The record from the source database is not migrated to the destination database. During incremental migration, DTS does not keep the record in the destination cluster. The record from the source database overwrites the record in the destination database. If the table schemas are inconsistent, data initialization may fail, only some columns of data are migrated, or the migration may fail.
      Index Name	Table Name If you select Table Name, the index created in the destination Elasticsearch instance has the same name as the table. Database Name_Table Name If you select Database Name_Table Name, the index created in the destination Elasticsearch instance is named in the format of `Database Name_Table Name`.
      Capitalization of Object Names in Destination Instance	You can configure the case-sensitivity policy for the names of databases, tables, and columns of the migration objects in the destination instance. By default, DTS Default Policy is selected. You can also select a policy that is consistent with the source or destination database. For more information, see Case-sensitivity of object names in the destination database.
      Source Objects	Select one or more objects from the Source Objects section. Click the icon and add the objects to the Selected Objects section. Note The migration objects can be databases or tables. If you select tables as migration objects, other objects such as views, triggers, and stored procedures are not migrated to the destination database.
      Selected Objects	To rename an object that you want to migrate 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 set a WHERE clause to filter data, or to set information such as the index name, type name, and column names after migration, right-click the table in the Selected Objects box and configure the settings in the dialog box that appears. For more information, see Set filter conditions. To select the SQL operations to be migrated at the database or table level, right-click the migration object in the Selected Objects box and select the desired SQL operations in the dialog box that appears. For information about the supported operations, see SQL operations supported for incremental migration.

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

      Configuration	Description
      Dedicated Cluster for Task Scheduling	By default, DTS schedules the data migration task to the shared cluster if you do not specify a dedicated cluster. If you want to improve the stability of data migration tasks, purchase a dedicated cluster. For more information, see What is a DTS dedicated cluster.
      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 retry time range. Valid values: 10 to 1,440. Unit: minutes. Default value: 720. We recommend that you set the parameter to a value greater than 30. If DTS is reconnected to the source and destination databases within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Note If you specify different retry time ranges for multiple data migration tasks that share the same source or destination database, the value that is specified later 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 the earliest opportunity after the source database and destination instance are released.
      Retry Time for Other Issues	The retry time range for other issues. For example, if DDL or DML operations fail to be performed after the data migration task is started, DTS immediately retries the operations within the retry time range. Valid values: 1 to 1440. Unit: minutes. Default value: 10. We recommend that you set the parameter to a value greater than 10. If the failed operations are successfully performed within the specified retry time range, DTS resumes the data migration task. Otherwise, the data migration task fails. Important The value of the Retry Time for Other Issues parameter must be smaller than the value of the Retry Time for Failed Connections parameter.
      Enable Throttling for Full Data Migration	Specifies whether to enable throttling for full data migration. During full data migration, DTS uses the read and write resources of the source and destination databases. This may increase the loads of the database servers. You can enable throttling for full data migration based on your business requirements. To configure throttling, you must configure the Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Full Data Migration for the Migration Types parameter.
      Enable Throttling for Incremental Data Migration	Specifies whether to enable throttling for incremental data migration. To configure throttling, you must configure the RPS of Incremental Data Migration and Data migration speed for incremental migration (MB/s) parameters. This reduces the loads of the destination database server. Note You can configure this parameter only if you select Incremental Data Migration for the Migration Types parameter.
      Environment Tag	If necessary, you can select an environment tag to identify the instance. In this example, no selection is needed.
      Shard Configuration	Set the number of primary shards and replica shards for the index based on the maximum shard configuration of the index in the destination Elasticsearch instance.
      String Index	Specifies the method to index strings that are migrated to the destination Elasticsearch instance. analyzed: Analyzes the string before indexing it. You also need to select a specific analyzer. For information about analyzer types and their functions, see Analyzers. not analyzed: Does not analyze the string. Indexes it using the original value. no: Does not index the string.
      Time Zone	When DTS migrates time-related data types such as DATETIME and TIMESTAMP to the destination Elasticsearch instance, you can select the time zone to include. Note If the time-related data types in the destination instance do not need a time zone, you must set the document type (type) for these data types in the destination instance before migration.
      DOCID	The DOCID defaults to the primary key of the table. If the table has no primary key, the DOCID is an ID column automatically generated by Elasticsearch.
      Whether to delete SQL operations on heartbeat tables of forward and reverse tasks	Specifies whether to write SQL operations on heartbeat tables to the source database while the DTS instance is running. Valid values: Yes: does not write SQL operations on heartbeat tables. In this case, a latency of the DTS instance may be displayed. No: writes SQL operations on heartbeat tables. In this case, features such as physical backup and cloning of the source database may be affected.
      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.
      Monitoring and Alerting	Specifies whether to configure alerting for the data migration task. If the task fails or the migration latency exceeds the specified threshold, the alert contacts receive notifications. Valid values: No: does not configure alerting. Yes: configures alerting. In this case, you must also configure the alert threshold and alert notification settings. For more information, see the Configure monitoring and alerting when you create a DTS task section of the Configure monitoring and alerting topic.

   3. After completing the configuration, click Next: Configure Database And Table Fields to set the _routing policy and _id value for the tables to be migrated in the destination Elasticsearch instance.

      Name	Description
      Set _routing	Setting _routing can route and store documents on a specified shard of the destination Elasticsearch instance. For more information, see _routing. Select Yes to use custom columns for routing. Select No to use the _id for routing. Note If the destination Elasticsearch instance you created is version 7.x, select No.
      _id Value	Primary Key Column A composite primary key is merged into a single column. Business Key If you select Business Key, you must also set the corresponding Business Key Column.

6. 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 migration task, DTS performs a precheck. You can start the data migration 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 issues. Then, run a precheck again.

     • If the 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.

7. Purchase the instance.

   1. Wait until Success Rate becomes 100%. Then, click Next: Purchase Instance.

   2. On the Purchase Instance page, configure the Instance Class parameter for the data migration instance. The following table describes the parameters.

      Section	Parameter	Description
      New Instance Class	Resource Group	The resource group to which the data migration instance belongs. Default value: default resource group. For more information, see What is Resource Management?
      	Instance Class	DTS provides instance classes that vary in the migration speed. You can select an instance class based on your business scenario. For more information, see Instance classes of data migration instances.

   3. Read and agree to Data Transmission Service (Pay-as-you-go) Service Terms by selecting the check box.

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

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

      Note

      • If a data migration task cannot be used to migrate incremental data, the task automatically stops. The Completed is displayed in the Status section.

      • If a data migration task can be used to migrate incremental data, the task does not automatically stop. The incremental data migration task never stops or completes. The Running is displayed in the Status section.