From Oracle to GaussDB(for MySQL)

Supported Source and Destination Databases

Suggestions

• The success of migration depends on environment and manual operations. You can run a migration test before you start the full-scale migration to help you detect and resolve problems in advance.
• Start your migration task during off-peak hours. A less active database is easier to migrate successfully. If the data is fairly static, there is less likely to be any severe performance impacts during the migration.
  • If network bandwidth is not limited, the query rate of the source database increases by about 50 MB/s during full migration, and two to four CPUs are occupied.
  • The data being migrated may be locked by other transactions for a long period of time, resulting in read timeout.
  • If DRS concurrently reads data from a database, it will use about 6 to 10 sessions. The impact of the connections on services must be considered.
  • If you read a table, especially a large table, during the full migration, the exclusive lock on that table may be blocked.
• Data-level comparison

  To obtain accurate comparison results, start data comparison at a specified time point during off-peak hours. If it is needed, select Start at a specified time for Comparison Time. Due to slight time difference and continuous operations on data, data inconsistency may occur, reducing the reliability and validity of the comparison results.

Precautions

Prerequisites

• You have logged in to the DRS console.
• For details about the DB types and versions supported by real-time migration, see Real-Time Migration.

• You have read Suggestions and Precautions.

Procedure

1. On the Online Migration Management page, click Create Migration Task.
2. On the Create Replication Instance page, specify the task name, description, and the replication instance details, and click Create Now.
   • Task information description

     Table 3 Task information

     Parameter	Description
     Task Name	The task name must start with a letter and consist of 4 to 50 characters. It can contain only letters, digits, hyphens (-), and underscores (_).
     Description	The description consists of a maximum of 256 characters and cannot contain special characters !=<>'&"\

   • Replication instance details

     Table 4 Replication instance settings

     Parameter	Description
     Data Flow	Select To the cloud. The destination database must be an RDS database on the current cloud.
     Source DB Engine	Select Oracle.
     Destination DB Engine	Select GaussDB(for MySQL).
     Network Type	Available options: VPN or Direct Connect and Public network. You can select a network type based on the site requirements. The following uses the public network as an example.
     Destination DB Instance	Select the DB instance you have created.
     Replication Instance Subnet	The subnet where the replication instance resides. You can also click View Subnets to go to the network console to view the subnet where the instance resides. By default, the DRS instance and the destination DB instance are in the same subnet. You need to select the subnet where the DRS instance resides, and there are available IP addresses for the subnet. To ensure that the replication instance is successfully created, only subnets with DHCP enabled are displayed.
     Migration Type	Full: This migration type is suitable for scenarios where service interruption is acceptable. All objects and data in non-system databases are migrated to the destination database at one time. The objects include tables, views, stored procedures, and triggers. NOTE: If you are performing a full migration, do not perform operations on the source database. Otherwise, data generated in the source database during the migration will not be synchronized to the destination database. Full+Incremental: This migration type allows you to migrate data without interrupting services. After a full migration initializes the destination database, an incremental migration initiates and parses logs to ensure data consistency between the source and destination databases. NOTE: If you select Full+Incremental, data generated during the full migration will be continuously synchronized to the destination database, and the source remains accessible.

   • Enterprise Project and Tags

     Table 5 Enterprise Project and Tags

     Parameter	Description
     Enterprise Project	An enterprise project you would like to use to centrally manage your cloud resources and members. Select an enterprise project from the drop-down list. The default project is default.
     Tags	Tags a task. This configuration is optional. Adding tags helps you better identify and manage your tasks. Each task can have up to 20 tags. After a task is created, you can view its tag details on the Tags tab. For details, see Tag Management.

   Note

   If a task fails to be created, DRS retains the task for three days by default. After three days, the task automatically stops.

3. On the Configure Source and Destination Databases page, wait until the replication instance is created. Then, specify source and destination database information and click Test Connection for both the source and destination databases to check whether they have been connected to the replication instance. After the connection tests are successful, select the check box before the agreement and click Next.

   Table 6 Source database settings

   Parameter	Description
   IP Address or Domain Name	The IP address or domain name of the source database.
   Port	The port of the source database. Range: 1 – 65535
   Database Service Name	You can use the database service name (Service Name or SID) to connect to Oracle databases from your client. Select Service Name or SID from the drop-down list and enter the corresponding value. Use a user with the DBA permissions to query its value: Use either of the following statements to query the service name: Statement 1: select value from v$parameter where name like '%service_name%'; Statement 2: show parameter service_name; Query the SID: select instance_name from V$instance;
   Database Username	The username for accessing the source database.
   Database Password	The password for the database username.
   SSL Connection	If SSL connection is required, enable SSL on the source database, ensure that related parameters have been correctly configured, and upload an SSL certificate. NOTE: The maximum size of a single certificate file that can be uploaded is 500 KB. If SSL is disabled, your data may be at risk.

   Note

   The IP address, port, username, and password of the source database are encrypted and stored in the database and the replication instance, and will be cleared after the task is deleted.

   Table 7 Destination database settings

   Parameter	Description
   DB Instance Name	The RDS DB instance you selected when creating the synchronization task. This parameter cannot be changed.
   Database Username	The username for accessing the destination database.
   Database Password	The password for the database username. The database username and password are encrypted and stored in DRS, and will be cleared after the task is deleted.
   SSL Connection	If SSL connection is required, enable SSL on the destination database, ensure that related parameters have been correctly configured, and upload an SSL certificate. NOTE: The maximum size of a single certificate file that can be uploaded is 500 KB. If SSL is disabled, your data may be at risk.

   Note

   The username and password of the destination database are encrypted and stored in the database and the replication instance during the migration. After the task is deleted, the username and password are permanently deleted.

4. On the Set Task page, select migration objects and click Next.

   Table 8 Migration Object

   Parameter

   Description

   Migration Object

   Tables: The selected table-level objects will be migrated. If the source database is changed, click in the upper right corner before selecting migration objects to ensure that the objects to be selected are from the changed source database. NOTE: If an object name contains spaces, the spaces before and after the object name are not displayed. If there are two or more consecutive spaces in the middle of the object name, only one space is displayed. The name of the selected migration object cannot contain spaces. To quickly select the desired database objects, you can use the search function.

5. On the Check Task page, check the migration task.
   • If any check fails, review the cause and rectify the fault. After the fault is rectified, click Check Again.
   • If the check is complete and the check success rate is 100%, click Next.
     Note

     You can proceed to the next step only when all checks are successful. If there are any items that require confirmation, view and confirm the details first before proceeding to the next step.

6. On the displayed page, specify Start Time, Send Notifications, SMN Topic, Delay Threshold (s), and Stop Abnormal Tasks After and confirm that the configured information is correct and click Submit to submit the task.

   Table 9 Task startup settings

   Parameter	Description
   Start Time	Set Start Time to Start upon task creation or Start at a specified time based on site requirements. The Start at a specified time option is recommended. NOTE: The migration task may affect the performance of the source and destination databases. You are advised to start the task in off-peak hours and reserve two to three days for data verification.
   Send Notifications	This parameter is optional. If the status, latency metric, or data of the migration task is abnormal, DRS will send you a notification.
   SMN Topic	This parameter is available only after you enable Send Notifications and create a topic on the SMN console and add a subscriber.

7. After the task is submitted, view and manage it on the Online Migration Management page.
   • You can view the task status. For more information about task status, see Task Statuses.
   • You can click in the upper right corner to view the latest task status.
   • After the full migration is complete, you can use data comparison to check whether the data is consistent before and after the migration.
   • By default, DRS retains a task in the Configuration state for three days. After three days, DRS automatically deletes background resources, but the task status remains unchanged. When you reconfigure the task, DRS applies for resources again.
   • For a public network task, DRS needs to delete background resources after you stop the task. The EIP bound to the task cannot be restored to the Unbound state until background resources are deleted.