The following table describes the various types of checkpoints taken in Teradata PT jobs.
| Checkpoint Type | Function |
|---|---|
| Basic (default) | If the tbuild command does not specify a checkpoint interval, the job automatically takes just two checkpoints during each job step that has consumer and producer operators:
These two checkpoints allow Teradata PT jobs to restart automatically without requiring user intervention, if the interruption was caused by a database server restart or deadlock situation. The default checkpoints can also be used for a manual restart. In either case, the job will restart after the last checkpoint written to the files.
This default checkpoint protection against redoing work is quite minimal, so Teradata recommends the use of interval checkpointing. |
| Interval Checkpointing | When you specify a checkpoint interval for a Teradata PT job using the tbuild -z command, the job takes a checkpoint for each specified interval (in seconds), for each job step with producer and consumer operators. If a job with interval checkpointing fails to run to completion and is later restarted, the only work that will have to be performed over again is the work done after the last checkpoint was taken. This option offers increased fault tolerance for long running jobs containing a substantial amount of data to be loaded/exported. The valid checkpoint interval values are between 0 and 86400. |
| Direct Command | A Teradata PT job can also be directed to take a checkpoint at any time through the twbcmd command, either explicitly with the JOB CHECKPOINT command option, or implicitly with the JOB PAUSE command option, which suspends job execution after the checkpoint is taken. For more information, see “Teradata PT Utility Commands” in Teradata® Parallel Transporter Reference, B035-2436. |
| Operator Initiated | The DataConnector operator automatically initiates a checkpoint after processing all the input files found during an interval-driven scan of a directory. |