Database change management

Background information

OceanBase Developer Center (ODC) allows you to change the data in your database. You can create a database change task to run time-consuming SQL statements to avoid an execution timeout.

Considerations

• A rollback statement can be automatically generated only for the UPDATE and DELETE statements.

• A change task is allowed to affect a maximum of 1 million rows. If the number of affected rows exceeds 1 million, a rollback statement cannot be automatically generated for this change task.

• If the table contains LOB fields, a rollback statement cannot be automatically generated.

• If the table does not have a primary or unique key when the data source is an OceanBase MySQL or a MySQL data source, a rollback statement cannot be automatically generated.

• If the SET and WHERE clauses in an UPDATE statement are the same, a rollback statement cannot be automatically generated.

• The maximum size of a rollback script that is automatically generated is 256 MB.

Create a database change task

Example: Change the value of name in the employee table in the odc_test database from xiaoguo to xiaofeng.

1. Choose Projects > All Projects. On the tab that appears, click the project name odc_4.2.0.

   

2. On the Tickets tab, choose Database Change > Create New.

   

3. In the Create Database Change Task panel, configure the following parameters.

   

   Parameter	Description
   Database	Select the database to which the database change task belongs.
   SQL Content	Select SQL Entry or Upload File. SQL Entry: This is the default way to specify SQL content. You can directly write the SQL script in the editing area. Note The maximum size of the SQL statements that can be entered in the SQL window is limited to 500,000 characters. If the SQL script to be executed has more than 500,000 characters, you can directly upload the script file. You can click IN Value Conversion to convert the batch copied data into the in('A','B') format. Column values are separated with line breaks. Row values are separated with spaces or tabs. Upload File: Click the file pool to go to the file explorer and select the file to be imported. You can also directly drag the file to the file pool to upload it. Note You can upload up to 500 files. The total file size cannot exceed 256 MB. By default, files are sorted by the order in which they were uploaded. You can drag and drop them to change the order. Tasks are executed in the file order. Only SQL files suffixed with .sql are supported.
   SQL Check	Click this icon to check the syntax of the SQL statement.
   Rollback Plan	Specify Rollback Plan. You can write an SQL script or upload a file to specify the rollback plan. For more information, see the description of SQL Content. Note You can select Generate Backup Rollback Plan so that backup rollback SQL statements will be automatically generated for UPDATE and DELETE statements. For OceanBase Database in MySQL mode or MySQL Database, a rollback SQL statement can be generated only for an UPDATE or DELETE statement executed on a table with a primary or unique key. A backup rollback SQL statement can be generated only when a database change statement affects no more than 100,000 rows and the database change task affects no more than 1 million rows.
   Delimiter	Delimiters are supported.
   Query Result Limit	You can set the maximum number of rows allowed in the query result. Value range: 1 to 1000000.
   Task Settings	SQL Retry Attempts: If you specify a value greater than 1, when the execution of an SQL statement fails, ODC will re-execute the statement in 3 minutes. The database change tool provides two error handling methods: Abort Task: This is the default option. When you select this option, the task is aborted if an error occurs when you run the script. Ignore Error and Continue: When you select this option, the system skips the erroneous statement where an error occurs and continues to execute other statements in the script. Select Execute Now or Scheduled Execution.
   Execution Timeout Value	Specify the value in the Execution Timeout Value field in hours. Default value: 48. Maximum value: 480.
   Description	You can enter a description of no more than 200 characters in Task Description. This field is optional.

4. Click Create.

5. On the Tickets tab, view the task information in the database change task list.

   

View a database change task

Task information

1. In the database change task list on the Tickets tab shown in the preceding figure, click View in the Actions column of the target task.

2. In the Task Details panel, click the Task Information tab to view the database, type, risk level, SQL content, and rollback statement of the task.

3. Click Initiate Again to initiate the database change task again, or click Roll Back to roll back the task.

Task process

In the Task Details panel, click the Task Process tab and view information such as the task initiation status, approval status, execution status, and execution result.

Execution result

In the Task Details panel, click the Execution Result tab to view the execution success and failure records.

Rollback ticket

In the Task Details panel, click Rollback Ticket to view the rollback task.

Task logs

In the Task Details panel, click the Task Logs tab to view all logs and alert logs of the task.

References

• Edit and execute SQL statements

• Perform PL compilation and debugging

• Use the command-line window

• Edit and export the result set of an SQL statement

• Analyze an SQL statement

• Generate test data

• Manage partitions

• Synchronization of shadow tables

• Lock-free schema changes