Enabling or Disabling Data Multi-Versioning (Deprecated, Not Recommended)

Function

The multi-versioning feature is to be deprecated and is not recommended.

DLI controls multiple versions of backup data for restoration. After the multiversion function is enabled, the system automatically backs up table data when you delete or modify the data using insert overwrite or truncate, and retains the data for a certain period. You can quickly restore data within the retention period. For details about the syntax related to the multiversion function, see Backing Up and Restoring Multi-Versioning Data (Deprecated, Not Recommended).

Currently, the multiversion function supports only OBS tables created using the Hive syntax. For details about the syntax for creating a table, see Creating an OBS Table Using the Hive Syntax.

Syntax

• Enable the multiversion function.

  ALTER TABLE [db_name.]table_name 
  SET TBLPROPERTIES ("dli.multi.version.enable"="true");

• Disable the multiversion function.

  1 2	ALTER TABLE [db_name.]table_name UNSET TBLPROPERTIES ("dli.multi.version.enable");

  After multiversion is enabled, data of different versions is automatically stored in the OBS storage directory when insert overwrite or truncate is executed. After multiversion is disabled, run the following statement to restore the multiversion backup data directory:

  RESTORE TABLE [db_name.]table_name TO initial layout;

Keywords

• SET TBLPROPERTIES: Used to set table properties and enable multiversion.
• UNSET TBLPROPERTIES: Used to unset table properties and disable multiversion.

Parameters

Precautions

Currently, the multiversion function supports only OBS tables created using the Hive syntax. For details about the syntax for creating a table, see Creating an OBS Table Using the Hive Syntax.

Example

• Modify the test_table table to enable multiversion.

  1 2	ALTER TABLE test_table SET TBLPROPERTIES ("dli.multi.version.enable"="true");

• Modify the test_table table to disable multiversion.

  1 2	ALTER TABLE test_table UNSET TBLPROPERTIES ("dli.multi.version.enable");

  Restore the multiversion backup data directory.

  RESTORE TABLE test_table TO initial layout;