# Limitations

The following limitations apply when Change Processing is enabled for the Teradata Database source:

* The "Start from timestamp" run option is not supported. For more information, see [Advanced run options](https://help.qlik.com/en-US/replicate/November2024/Content/Global_Common/Content/SharedEMReplicate/Tasks%20at%20Runtime/monitor_detailed_run_options.htm).

* If one of the Context columns is part of the Primary Key or Unique Index, then UPDATE and DELETE operations are not supported.

* Context columns cannot be LOB columns

* DDLs are not supported

* When inserting a record and then updating the same record, the task error handling settings should be set as follows:

  1. Open the <Task Name> Settings dialog box.
  2. Select the Error Handling|Apply Conflicts tab.
  3. Set a task-specific Apply Conflicts policy as described in [Error Handling settings](https://help.qlik.com/en-US/replicate/November2024/Content/Global_Common/Content/SharedEMReplicate/Customize%20Tasks/tasks_errHandSettStab.htm).
  4. From the No record found for applying an update drop-down list, select INSERT the missing target record.

  For more information on error handling, see [Error handling](https://help.qlik.com/en-US/replicate/November2024/Content/Global_Common/Content/SharedEMReplicate/Customize%20Tasks/tasks_errHand.htm).