The Update operator takes a checkpoint at the beginning and the end of the acquisition phase. More granular checkpoints during the acquisition phase can be specified using the -z option of the tbuild command, which specifies checkpoint intervals in terms of seconds. For example:
tbuild -f <file name> -z 120
In this example, the -f option specifies the name of the script that is input to tbuild, and the -z option indicates that a checkpoint is taken every 120 seconds.
For more information about checkpoints and restarts, see the Teradata Parallel Transporter User Guide (B035-2445).
The Update operator cannot be rolled back. Once changes are applied to target tables in the application phase, a job can only move forward.
Since a target table cannot be returned to its original state, it is advisable to archive tables prior to running Update operations against them.
To restart a job from the beginning (and bypass the restart log table) do the following:
- Drop the restart log table.
- Drop the error and work tables.
- Drop the checkpoint files.
To discontinue an Update operation and drop the target tables, do the following:
- Drop the restart log table.
- Drop the error and work tables.
- Drop the target tables.