Migrate Tencent Cloud MySQL to Alibaba Cloud

Prerequisites

• An Alibaba Cloud RDS instance has been created. You can create an Alibaba Cloud RDS instance if you do not have one.

• An account with read and write permissions has been created. You can create an account with read and write permissions if you do not have one.

Migration limitations

• Structure migration does not support the migration of events.

• DTS reads values from FLOAT or DOUBLE columns by using the ROUND(COLUMN,PRECISION) function. If you do not explicitly define a precision, DTS migrates FLOAT data with a precision of 38 and DOUBLE data with a precision of 308. Verify that the migration precision meets your business requirements.

• If you use the object name mapping feature, the migration of dependent objects might fail.

• When you perform an incremental migration, binlog must be enabled on the source MySQL instance.

• For an incremental migration, the binlog_format parameter on the source database must be ROW.

• For an incremental migration, if the source MySQL instance is version 5.6 or later, its binlog_row_image parameter must be full.

Considerations

• During a full data migration, DTS consumes read and write resources on the source and destination databases, increasing their load. If your databases have poor performance, low specifications, or high workloads (for example, if the source database has many slow SQL queries or tables without primary keys, or if deadlocks occur in the destination database), the increased load can strain your databases or even cause service interruptions. Perform the data migration during off-peak hours, such as when the CPU utilization of both databases is below 30%.

• If a source table lacks a primary key or a unique constraint and contains non-unique data, duplicate data may be created in the destination database.

• DTS automatically attempts to recover any migration task that has failed within the last seven days. This recovery process may cause source data to overwrite application data in the destination database. After the migration task is complete, you must revoke the write permission from the DTS account for the destination database with the revoke command.

Prerequisites

You can find the public IP address at the bottom of the Basic Information section on the Instance Details tab. Once enabled, the public IP will display its full domain name and port.

Procedure (new console)

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. Optional: In the upper-right corner of the page, click New Configuration Page.

   Note

   • If you are already on the new configuration page (the button in the upper-right corner is Back to Previous Version), you can skip this step.

   • The parameters on the new and old configuration pages are different. We recommend that you use the new configuration page.

4. Configure the source and destination databases.

   Warning

   After you select the source and destination instances, we recommend that you carefully read the limits displayed at the top of the page. Otherwise, the task may fail or data inconsistency may occur.

   Category	Setting	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 MySQL.
   	Access Method	Select Public IP. Note You can click Get DTS IP Segments on the right to view and copy the CIDR blocks for the corresponding region. If your instance has restricted access, you must add the public IP CIDR blocks for the corresponding region to the allowlist before you configure the migration task.
   	Instance Region	Select the region where the Tencent Cloud MySQL database is located. Note If your Tencent Cloud MySQL database's region is not listed, select the nearest one.
   	Domain Name or IP	Enter the domain name part of the public endpoint for the Tencent Cloud MySQL database.
   	Port	Enter the port number of the public endpoint for the Tencent Cloud MySQL database.
   	Database Account	Enter the default privileged account for the Tencent Cloud MySQL database: root.
   	Database Password	Enter the password for the database account.
   	Encryption	Select Non-encrypted or SSL-encrypted. If SSL encryption is not enabled for the Tencent Cloud MySQL database, select Non-encrypted. If SSL encryption is enabled for the Tencent Cloud MySQL database, select SSL-encrypted. You also need to upload the CA Certificate and enter the CA Certificate Password.
   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 MySQL.
   	Access Method	Select Alibaba Cloud Instance.
   	Instance Region	Select the region where the destination RDS for MySQL instance is located.
   	Replicate Data Across Alibaba Cloud Accounts	In this example, a database instance under the current Alibaba Cloud account is used. Select No.
   	RDS Instance ID	Select the ID of the destination RDS for MySQL instance.
   	Database Account	Enter the account for the destination RDS for MySQL instance. This account must have read and write permissions.
   	Database Password	Enter the password for the database account.
   	Encryption	Select Non-encrypted or SSL-encrypted based on your database requirements. If you set this parameter to SSL-encrypted, you must enable SSL encryption for the RDS for MySQL instance beforehand. For more information, see Quickly enable SSL encryption using a cloud certificate.

5. After you complete the configuration, click Test Connectivity and Proceed at the bottom of the page. In the CIDR Blocks of DTS Servers dialog box that appears, click Test Connectivity.

   Note

   Ensure that the IP address segments of the DTS service are 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.

6. Configure the task objects.

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

      Setting	Description
      Migration Types	If you only need to perform a full migration, select both Schema Migration and Full Data Migration. To perform a migration with no downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Schema Migration, you must ensure that a database and tables to receive the data exist in the destination database. You can also use the object name mapping feature in the Selected Objects box as needed. If you do not select Incremental Data Migration, do not write new data to the source instance during data migration to ensure data consistency.
      Method to Migrate Triggers in Source Database	Select a method to migrate triggers based on your requirements. If the objects you want to migrate do not involve triggers, you do not need to configure this setting. For more information, see Configure the method to synchronize or migrate triggers. Note This setting is available only if you select Schema Migration for Migration Types.
      Enable Migration Assessment	This feature assesses whether the schemas of the source and destination databases (such as index length, stored procedures, and dependent tables) meet the requirements. Select Yes or No based on your requirements. Note This setting is available only if you select Schema Migration for Migration Types. If you select Yes, the precheck time may increase. You can view the Assessment Result during the precheck phase. The assessment result does not affect the precheck result.
      Processing Mode of Conflicting Tables	Precheck and Report Errors: Checks whether tables with the same names exist in the destination database. If no tables with the same names exist, the precheck is passed. If tables with the same names exist, an error is reported during the precheck, and the data migration task does not start. Note If a table in the destination database has the same name but cannot be easily deleted or renamed, you can change the name of the table in the destination database. For more information, see Object name mapping. Ignore Errors and Proceed: Skips the check for tables with the same names. Warning Selecting Ignore Errors and Proceed may cause data inconsistency and business risks. 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 database. The record from the source database is not migrated. During incremental migration, DTS does not keep the record in the destination database. The record from the source database overwrites the record in the destination database. If the table schemas are inconsistent, only some columns of data may be migrated, or the migration may fail. Proceed with caution.
      Whether to migrate Event	Select whether to migrate events from the source database. If you select Yes, you must also follow the relevant requirements and perform subsequent operations. For more information, see Synchronize or migrate events.
      Capitalization of Object Names in Destination Instance	You can configure the case sensitivity policy for the names of migrated objects, such as databases, tables, and columns, in the destination instance. By default, DTS default policy is selected. You can also choose to keep the case sensitivity consistent with the default policy of 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 granularity for selecting migration objects is database, table, and column. If you select only tables or columns as migration objects, other objects such as views, triggers, and stored procedures are not migrated to the destination database.
      Selected Objects	To change the name of a single migration object in the target instance, right-click the object in the Selected Objects box. For more information, see Map individual schema, table, and column names. To change the names of multiple migration objects in the target instance, click Selected Objects in the upper-right corner of the Batch Edit box. For more information, see Map multiple schema, table, and column names. Note If you use the object name mapping feature, other objects that depend on the mapped object may fail to migrate. To filter data by using a WHERE clause, right-click the table to be migrated in the Selected Objects box and set the filter conditions in the dialog box that appears. For instructions, see Configure filter conditions. To select the SQL operations to migrate 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 parameters.

      Setting	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.
      Copy the temporary table of the Online DDL tool that is generated in the source table to the destination database.	If you use Data Management (DMS) or gh-ost to perform online DDL changes in the source database, you can choose whether to migrate the data from the temporary tables generated by the online DDL changes. Important DTS tasks do not support using tools such as pt-online-schema-change to perform online DDL changes. Otherwise, the DTS task fails. The processing methods for each phase are as follows: The Schema Migration and Full Data Migration phases do not allow DDL operations that change the database or table structure. Therefore, they are not controlled by the online DDL policy. Schema Migration: Not controlled by the online DDL policy. Related temporary tables are created. Full Data Migration: Not controlled by the online DDL policy. The migration of temporary tables is not included in the full migration objects. All tables whose names match the regular expression (^_(.+)_(?:gho|new)$ or ^_(.+)_(?:ghc|del|old)$) are filtered out. Incremental Data Migration: Controlled by the online DDL policy. Yes: Migrates data changes from temporary tables (for example, _table_name_gho) generated by online DDL operations. No, Adapt to DMS Online DDL and No, Adapt to gh-ost: Filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules. Yes: Migrates the data from the temporary tables generated by online DDL changes. Note If online DDL changes generate a large amount of data in temporary tables, it may cause task latency. No, Adapt to DMS Online DDL: Does not migrate the data from the temporary tables generated by online DDL changes. It only migrates the original DDL statements executed using Data Management (DMS). Note This option causes tables in the destination database to be locked. No, Adapt to gh-ost: Does not migrate the data from the temporary tables generated by online DDL changes. It supports custom filtering rules. DTS filters out data changes from temporary tables (for example, _table_name_gho) generated by tools such as gh-ost based on regular expression rules. You can modify the default regular expressions used to match shadow and useless tables as needed: Shadow table: ^_(.+)_(?:gho|new)$ Useless table: ^_(.+)_(?:ghc|del|old)$ Note This option causes tables in the destination database to be locked.
      Whether to Migrate Accounts	Select whether to migrate account information from the source database. If you select Yes, you also need to select the accounts to migrate and confirm their permissions. For more information, including authorization methods, see Migrate database accounts.
      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.
      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.
      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.
      Environment Tag	You can select an environment tag to identify the instance. This is not required for this example.
      Configure ETL	Based on your business needs, select whether to configure the ETL feature to process data. Yes: Configures the ETL feature. You must also enter data processing statements in the text box. No: Does not configure 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 contact. If a migration fails or the latency exceeds the threshold, the system sends an alert notification.

   3. Click Next: Data Validation to configure a data validation task.

      For more information about the data validation feature, see Configure data validation.

7. 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.

8. 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.

Procedure (old console)

1. Log in to the DTS console.

   Note

   If the Data Transmission Service (DTS) console automatically redirects to the Data Management (DMS) console, you can click the icon in the lower-right corner and then click Return to Old Version in the dialog box to return to the old DTS console.

2. In the left navigation pane, click Data Migration. In the upper-right corner, click Create Migration Task.

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

   Database category	Parameter	Description
   Source database	Instance type	The type of the source instance. Select Self-managed database with public IP.
   	Instance region	If your instance has restricted access, you must add the public IP CIDR blocks for the corresponding region to the allowlist before you configure the migration task. Note You can click Get DTS IP Segments on the right to view and copy the CIDR blocks for the corresponding region.
   	Database type	The type of the source database. Select MySQL.
   	Hostname or IP address	The Tencent Cloud database's public address's domain name portion.
   	Port	The public IP address's port section for a Tencent Cloud database.
   	Database account	The account for the source database. For example, root.
   	Database password	The password for the source database account.
   Destination database	Instance type	The type of the destination instance. Select RDS instance.
   	Instance region	The region of the destination instance.
   	RDS instance ID	Select the ID of the destination RDS instance.
   	Database account	An account of the destination instance that has read and write permissions.
   	Database password	The password for the destination instance account.
   	Connection method	Two connection methods are available: Non-encrypted Transmission and SSL Secure Connection. Selecting SSL secure connection significantly increases the CPU utilization of the RDS for MySQL instance.

4. After you complete the configuration, click Test Connection and verify that the connections to both the source and destination databases are successful.

5. Click Authorize Allowlist and Go to Next Step.

   For Alibaba Cloud sources and destinations (such as ApsaraDB RDS or ECS-hosted databases), DTS automatically adds its server CIDR blocks to the whitelist or security group. For external databases, such as those in a data center or on another cloud, you must manually add the CIDR blocks to grant DTS access. For the IP addresses to add, see CIDR blocks of DTS servers.

   Warning

   Adding the public CIDR blocks of DTS servers, whether automatically or manually, may introduce security risks. By using this product, you acknowledge and accept these potential risks. You are responsible for implementing basic security measures, including but not limited to using strong passwords, restricting open ports, using authentication for internal API calls, regularly reviewing and restricting unnecessary network segments, or connecting through private networks such as Express Connect, VPN Gateway, or Smart Access Gateway.

6. Select the migration objects and migration types.

   Note

   To ensure data consistency, we recommend selecting schema migration, full data migration, and incremental data migration.

   Parameter	Description
   Migration type	If you only need to perform a full migration, select both Schema Migration and Full Data Migration. For a migration with minimal downtime, select Schema Migration, Full Data Migration, and Incremental Data Migration. Note If you do not select Incremental Data Migration, do not write new data to the source database during the data migration to ensure data consistency.
   Object name mapping	To change the name of a migration object in the destination instance, use the object name mapping feature. For more information, see Map schemas, tables, and columns.
   Retry duration upon connection failure	The default retry duration is 12 hours, but you can customize this duration. If DTS successfully reconnects to the source and destination databases within the specified duration, the migration task automatically resumes. Otherwise, the task fails. Note Because DTS charges for task runtime during the connection retry period, we recommend that you customize the retry duration based on your business needs or release the DTS instance as soon as the source and destination instances are released.
   Replicate temporary tables created by online DDL in DMS	If you use Data Management (DMS) to perform online DDL changes in the source database, you can choose whether to migrate data from the temporary tables that are generated by these changes. Yes: Migrates data from temporary tables generated by online DDL changes. Note Large amounts of data in temporary tables generated by online DDL changes may cause migration task latency. No: Does not migrate data from temporary tables generated by online DDL changes. Only the original DDL data from the source database is migrated. Note This option causes table locking in the destination database.

7. After you complete these settings, click Pre-check and Start in the lower-right corner of the page.

   Note

   • DTS performs a precheck before the task starts. The task can start only after it passes the precheck.

   • If the precheck fails, click the icon next to the failed item to view details.

     • Fix the issues based on the details, and then run the precheck again.

     • For warnings that do not require a fix, you can select Ignore or Ignore and Rerun Precheck to run the precheck again.

8. Click Next. In the Confirm Purchase Configuration dialog box, select the Data Transmission Service (pay-as-you-go) Terms of Service checkbox and click Purchase and Start Now.

   Note

   Schema migration and full data migration tasks are free of charge. Incremental data migration is charged hourly based on the link specification.

9. Wait for the migration to complete. While the task is in progress, its Status is Running. The Phase column shows that Schema Migration and Full Migration are complete.