Data Transmission Service:Migrate data from PolarDB-X 2.0 to Elasticsearch

Prerequisites

• A source PolarDB-X 2.0 instance is created.

• A destination Elasticsearch instance is created. For more information, see Create an Alibaba Cloud Elasticsearch instance.

• The versions of the source and destination instances are supported. For more information, see Migration solutions.

• The storage space of the destination Elasticsearch instance must be larger than that of the source PolarDB-X 2.0 instance.

Precautions

Billing

Migration types

• 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 data migration

Permissions required for database accounts

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.

   Warning

   After you configure the source and destination databases, we recommend that you read the Limits that are displayed in the upper part of the page. Otherwise, the task may fail or data inconsistency may occur.

   Category	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-X 2.0.
   	Access Method	Select Cloud Instance.
   	Instance Region	Select the region where the source PolarDB-X 2.0 instance resides.
   	Replicate Data Across Alibaba Cloud Accounts	This example is for a migration within the same Alibaba Cloud account. Select No.
   	Instance ID	Select the ID of the source PolarDB-X 2.0 instance.
   	Database Account	Enter the database account of the source PolarDB-X 2.0 instance. For information about the required permissions, see Permissions required for database accounts.
   	Database Password	The password that is used to access the database instance.
   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 Edition or Serverless based on your actual needs.
   	Instance ID	Select the ID of the destination Elasticsearch instance.
   	Database Account	Enter the database account of the destination Elasticsearch instance. The default account is elastic. For information about the required permissions, see Permissions required for database accounts.
   	Database Password	The password that is used to access the database instance.
   	Encryption	Select HTTP or HTTPS based on your actual scenario.

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.

      Parameter	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.
      Index Name	Table Name If you select Table Name, the name of the index created in the destination Elasticsearch instance is the same as the table name. For example, the index name is order. Database Name_Table Name If you select Database Name_Table Name, the name of the index created in the destination Elasticsearch instance is Database Name_Table Name. In this example, the index name is dtstest_order.
      Processing Mode of Conflicting Tables	Precheck and Report Errors: checks whether the destination database contains tables that use the same names as tables in the source database. If the source and destination databases do not contain tables that have identical table names, the precheck is passed. Otherwise, an error is returned during the precheck and the data migration task cannot be started. Note If the source and destination databases contain tables with identical names and the tables in the destination database cannot be deleted or renamed, you can use the object name mapping feature to rename the tables that are migrated to the destination database. For more information, see Map object names. Ignore Errors and Proceed: skips the precheck for identical table 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 the following potential risks: If the source and destination databases have the same schema, and a data record has the same primary key as an existing data record in the destination database, the following scenarios may occur: During full data migration, DTS does not migrate the data record to the destination database. The existing data record in the destination database is retained. During incremental data migration, DTS migrates the data record to the destination database. The existing data record in the destination database is overwritten. If the source and destination databases have different schemas, only specific columns are migrated or the data migration task fails. Proceed with caution.
      Capitalization of Object Names in Destination Instance	You can configure the case policy for the names of databases, tables, and columns in the destination instance. By default, DTS Default Policy is selected. You can also choose to use the same policy as the source database or the destination database. For more information, see Case Policy for Destination Database Object Names.
      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 You can select columns, tables, or schemas as the objects to be migrated. If you select tables or columns as the objects to be migrated, DTS does not migrate other objects, such as views, triggers, or stored procedures, 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 If you use the object name mapping feature, other objects that depend on the mapped object might not be migrated. To filter data using a WHERE condition, right-click the table that you want to migrate in the Selected Objects box and set the filter condition in the dialog box that appears. For more information, see Filter task data using SQL conditions. To select the SQL operations for migration at the database or table level, right-click the object in the Selected Objects box and select the desired SQL operations in the dialog box that appears.

   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	You can select an environment tag to identify the instance. In this example, no tag is selected.
      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 used to index strings that are migrated to the destination Elasticsearch instance. analyzed: The strings are analyzed before they are indexed. You must also select a specific analyzer. For more information about analyzer types and their functions, see Analyzers. not analyzed: The strings are indexed with their original values and are not analyzed. no: The strings are not indexed.
      Time Zone	You can select a time zone for time-related data types, such as DATETIME and TIMESTAMP, that DTS migrates to the destination Elasticsearch instance. Note If the time-related data types in the destination instance do not require 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 does not have a primary key, the DOCID is an ID column that is 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. In the lower part of the page, click Next: Configure Database and Table Fields. On the page that appears, set the _routing policy and _id value for the tables that you want to migrate to the destination Elasticsearch cluster.

      Category	Description
      Set _routing	Specifies whether to store a document on a specific shard of the destination Elasticsearch cluster. For more information, see _routing. Valid values: Yes: You can specify custom columns for routing. No: The _id value is used for routing. Note If the version of the destination Elasticsearch cluster is 7.x, you must select No.
      Value of _id	Primary key column Multiple columns are merged into one composite primary key. Business key If you select a business key, you must also specify the 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.

View the migrated indexes and data

After the data migration task enters the Running state, you can use the Kibana data visualization software to connect to the Elasticsearch instance. This lets you confirm whether the created index and migrated data meet your business requirements. For more information about how to log on to the Kibana console, see Log on to the Kibana console.