16.10 - Checkpoints and Restarts - Access Module

Teradata Tools and Utilities Access Module Reference

prodname
Access Module
vrm_release
16.10
created_date
July 2017
category
Programming Reference
featnum
B035-2425-077K
Checkpoint and restart operations are not supported for export jobs (unloading data); however, checkpoints and restarts are supported for load jobs (loading data). Restarts for load operations are only supported when the following conditions are met:
  • The data being loaded does not change between the initial load attempt and the restart.

    Check the source data to make sure it has not changed between the initial load attempt and the restart. The Teradata Access Module for OLE DB does not check for changed data during the restart operation. If the data has changed, the loaded data may not reflect the true contents of the source table.

  • To load data from the most recent checkpoint, the Enable scroll backwards option must be selected on the Advanced Settings dialog box before the job starts.
The following can occur during checkpoint/restart operations:
  • If a load process loses contact with the destination Teradata Database (for example, the destination Teradata Database resets), the Teradata Access Module for OLE DB backs up to the previous checkpoint location, and resumes retrieving and returning data from that location when contact is restored (at the request of the load utility).
  • If a load process terminates unexpectedly, manually restart the load job by reissuing the job. In this case, the Teradata Database detects that a restart is in progress and (at the request of the load utility) the Teradata Access Module for OLE DB skips forward to the previous checkpoint location, and resumes retrieving and returning data from that location.
For bulk load operations, the number of rows displayed in the progress dialog box might not be the same as the number of rows returned to the utility if a restart occurs. In this case, the progress dialog box might display a larger number of row retrievals than the number of rows actually retrieved from the data source.