Data Transmission Service:Synchronize PolarDB for MySQL to Elasticsearch

Prerequisites

You have created an Elasticsearch instance in the destination region. The storage space of this instance must be larger than that of the source PolarDB for MySQL cluster. For more information, see Create an Alibaba Cloud Elasticsearch instance.

Important notes

Billing

Supported SQL operations

Database account permissions

Procedure

1. Go to the data synchronization task list page in the destination region. You can do this in one of two ways.

   DTS console

   1. Log on to the DTS console.

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

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

   DMS console

   Note

   The actual steps may vary depending 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 DMS console.

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

   3. To the right of Data Synchronization Tasks, select the region of the synchronization instance.

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

3. Configure the source and destination databases.

   Category	Configuration	Description
   None	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	Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured. Note In the DMS console, this configuration item is Select a DMS database instance. If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.
   	Database Type	Select PolarDB for MySQL.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	Select the region where the source PolarDB for MySQL cluster resides.
   	Replicate Data Across Alibaba Cloud Accounts	For this example, select No, as the database instance belongs to the current Alibaba Cloud account.
   	PolarDB Cluster ID	Select the ID of the source PolarDB for MySQL cluster.
   	Database Account	Enter the database account for the source PolarDB for MySQL cluster. For permission requirements, see Database account permissions.
   	Database Password	Enter the password for the specified database account.
   	Encryption	Select as needed. For more information about SSL encryption, see Configure SSL encryption.
   Destination Database	Select Existing Connection	Select the registered database instance with DTS from the drop-down list. The database information below is automatically configured. Note In the DMS console, this configuration item is Select a DMS database instance. If you have not registered the database instance or do not need to use a registered instance, manually configure the database information below.
   	Database Type	Select Elasticsearch.
   	Access Method	Select Alibaba 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 default login name elastic for the Elasticsearch instance.
   	Database Password	Enter the password for the specified database account.
   	Encryption	Select HTTP or HTTPS as needed.

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

   Note

   • Ensure that you add the CIDR blocks of the DTS servers (either automatically or manually) to the security settings of both the source and destination databases to allow access. For more information, see Add the IP address whitelist of DTS servers.

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

5. Configure the task objects.

   1. On the Configure Objects page, specify the objects to synchronize.

      Configuration	Description
      Synchronization Types	DTS always selects Incremental Data Synchronization. By default, you must also select Schema Synchronization and Full Data Synchronization. After the precheck, DTS initializes the destination cluster with the full data of the selected source objects, which serves as the baseline for subsequent incremental synchronization.
      Index Name	If you select Table Name, the index name created in the destination Elasticsearch instance is the same as the table name. If you select Database Name_Table Name, the index name created in the destination Elasticsearch instance is a concatenation of the database name, an underscore (_), and the table name. Note The index name mapping configuration takes effect for all tables.
      Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks for tables with the same names in the destination database. If any tables with the same names are found, an error is reported during the precheck and the data synchronization task does not start. Otherwise, the precheck is successful. Note If you cannot delete or rename the table with the same name in the destination database, you can map it to a different name in the destination. For more information, see Database Table Column Name Mapping. Ignore Errors and Proceed: Skips the check for tables with the same name in the destination database. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and put your business at risk. For example: If the table schemas are consistent and a record in the destination database has the same primary key or unique key value as a record in the source database: During full data synchronization, DTS retains the destination record and skips the source record. During incremental synchronization, DTS overwrites the destination record with the source record. If the table schemas are inconsistent, data initialization may fail. This can result in only partial data synchronization or a complete synchronization failure. Use with caution.
      Capitalization of Object Names in Destination Instance	Configure the case-sensitivity policy for database, table, and column names in the destination instance. By default, the DTS default policy is selected. You can also choose to use the default policy of the source or destination database. For more information, see Case policy for destination object names.
      Source Objects	In the Source Objects box, click the objects, and then click to move them to the Selected Objects box. Note You can select objects at the database or table level.
      Selected Objects	To modify the index name, type name, field name, or filter condition for a table in the destination Elasticsearch instance, right-click the table name in the Selected Objects area. For more information, see Map database and table column names and Set filter conditions. Note Only underscores (_) are allowed as special characters in index and type names.

   2. Click Next: Advanced Settings.

      Configuration	Description
      Dedicated Cluster for Task Scheduling	By default, DTS uses a shared cluster for tasks, so you do not need to make a selection. For greater task stability, you can purchase a dedicated cluster to run the DTS synchronization task. For more information, see What is a DTS dedicated cluster?.
      Retry Time for Failed Connections	If the connection to the source or destination database fails after the synchronization task starts, 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 1,440 minutes. We recommend a duration of 30 minutes or more. If the connection is restored within this period, the task resumes automatically. Otherwise, the task fails. Note If multiple DTS instances (e.g., Instance A and B) share a source or destination, DTS uses the shortest configured retry duration (e.g., 30 minutes for A, 60 for B, so 30 minutes is used) for all instances. DTS charges for task runtime during connection retries. Set a custom duration based on your business needs, or release the DTS instance promptly after you release the source/destination instances.
      Retry Time for Other Issues	If a non-connection issue (e.g., a DDL or DML execution error) occurs, DTS reports an error and immediately retries the operation. The default retry duration is 10 minutes. You can also customize the retry time to a value from 1 to 1,440 minutes. We recommend a duration of 10 minutes or more. If the related operations succeed within the set retry time, the synchronization task automatically resumes. Otherwise, the task fails. Important The value of Retry Time for Other Issues must be less than that of Retry Time for Failed Connections.
      Enable Throttling for Full Data Synchronization	During full data synchronization, DTS consumes read and write resources from the source and destination databases, which can increase their load. To mitigate pressure on the destination database, you can limit the migration rate by setting Queries per second (QPS) to the source database, RPS of Full Data Migration, and Data migration speed for full migration (MB/s). Note This parameter is available only if Synchronization Types is set to Full Data Synchronization. You can also adjust the rate of full data synchronization when the synchronization instance is running.
      Enable Throttling for Incremental Data Synchronization	You can also limit the incremental synchronization rate to reduce pressure on the destination database by setting RPS of Incremental Data Synchronization and Data synchronization speed for incremental synchronization (MB/s).
      Environment Tag	Select an environment label to identify the instance as needed. This example does not require one.
      Shard Configuration	Set the number of primary and replica shards for the index, based on the maximum shard configuration in the destination Elasticsearch instance.
      String Index	How strings are indexed in the destination Elasticsearch instance. analyzed: Analyze the string first, then index it. You must also select an analyzer. For analyzer types and functions, see Analyzers. not analyzed: Index the raw value directly without analysis. no: Do not index the string.
      Time Zone	When synchronizing DATETIME or TIMESTAMP data types to the destination Elasticsearch instance, select the time zone to use. Note If time zone information is not needed for these data types in the destination instance, pre-configure the document type (type) for this data in the destination instance.
      DOCID	No configuration required. DOCID defaults to the table's primary key. If no primary key exists, DOCID is the ID column auto-generated by Elasticsearch.
      Whether to delete SQL operations on heartbeat tables of forward and reverse tasks	Choose whether DTS writes heartbeat SQL information to the source database while the instance is running. Yes: Does not write heartbeat SQL information to the source database. The DTS instance may display latency. No: Writes heartbeat SQL information to the source database. This may interfere with source database operations like physical backups and cloning.
      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	Choose whether to set up alerts. If the synchronization fails or the latency exceeds the specified threshold, DTS sends a notification to the alert contacts. No: No alerts are configured. Yes: Configures alerts. You must also set the alert threshold and alert notifications. For more information, see Configure monitoring and alerting during task configuration.

   3. After completing the above configurations, click Next: Configure Database and Table Fields to set the _routing strategy and _id value for tables in the destination Elasticsearch instance.

      Note

      You can select Definition Status as All to make changes.

      Type	Description
      Set _routing	Configuring _routing routes documents to specific shards in the destination Elasticsearch instance. For more information, see _routing. Select Yes to define a custom column for routing. Select No to route using _id. Note If the destination Elasticsearch instance is version 7.x, select No.
      _routing Column	Select the column to use for routing. Note This parameter is required only when Set _routing is set to Yes.
      Value of _id	Select the column to use as the document ID.

6. Save the task and perform a precheck.

   • To view the parameters for configuring this instance via an API operation, hover over the Next: Save Task Settings and Precheck button and click Preview OpenAPI parameters in the tooltip.

   • If you have finished viewing the API parameters, click Next: Save Task Settings and Precheck at the bottom of the page.

   Note

   • Before a synchronization task starts, DTS performs a precheck. You can start the task only if the precheck passes.

   • If the precheck fails, click View Details next to the failed item, fix the issue as prompted, and then rerun the precheck.

   • If the precheck generates warnings:

     • For non-ignorable warning, click View Details next to the item, fix the issue as prompted, and run the precheck again.

     • For ignorable warnings, you can bypass them by clicking Confirm Alert Details, then Ignore, and then OK. Finally, click Precheck Again to skip the warning and run the precheck again. Ignoring precheck warnings may lead to data inconsistencies and other business risks. Proceed with caution.

7. Purchase the instance.

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

   2. On the Purchase page, select the billing method and link specifications for the data synchronization instance. For more information, see the following table.

      Category	Parameter	Description
      New Instance Class	Billing Method	Subscription: You pay upfront for a specific duration. This is cost-effective for long-term, continuous tasks. Pay-as-you-go: You are billed hourly for actual usage. This is ideal for short-term or test tasks, as you can release the instance at any time to save costs.
      	Resource Group Settings	The resource group to which the instance belongs. The default is default resource group. For more information, see What is Resource Management?.
      	Instance Class	DTS offers synchronization specifications at different performance levels that affect the synchronization rate. Select a specification based on your business requirements. For more information, see Data synchronization link specifications.
      	Subscription Duration	In subscription mode, select the duration and quantity of the instance. Monthly options range from 1 to 9 months. Yearly options include 1, 2, 3, or 5 years. Note This option appears only when the billing method is Subscription.

   3. Read and select the checkbox for Data Transmission Service (Pay-as-you-go) Service Terms.

   4. Click Buy and Start, and then click OK in the OK dialog box.

      You can monitor the task progress on the data synchronization page.