Restarts on TPump Jobs with Identity Column
TPump works on multistatement SQL requests. Each request has a specific number of statements depending on the PACK specification in the BEGIN LOAD command.
In ROBUST mode, each request is written into a restart log table.
If a restart occurs, TPump will query the restart log table and re-execute requests that are not logged. This means it may be possible for a restart to generate duplicates if an insert request is repeated. Duplicates will not be detected if the target table is not defined with a UPI.
TPump will flag an error if it is run in simple mode and the target table has an identity column PI. This is because no restart log is used for restart recovery and duplicate rows could result if some requests are reprocessed.
For more information on this utility, see Teradata Parallel Data Pump Reference.