Some tables are created during the execution of a job, and others must be created by the user before the job begins. With the Update operator, target tables must exist on the Teradata Database when the Update operator job is executed. The log table is created automatically when you run the Update job script. Error tables and work tables are created by the Teradata Database.
Error tables are dropped by the Update operator during the cleanup phase if no errors are detected during the acquisition phase or the application phase. The work table is dropped by the Update operator during the cleanup phase if no errors are detected during the acquisition phase or the application phase. The log table is dropped by the Update operator after the job completes successfully.
If a job terminates abnormally, then the log, error, and work tables may not be dropped, depending on where in the job the termination occurs. If you want to restart the job from scratch, you must manually drop these tables by running a BTEQ script.
Care must be taken if the target tables are manually dropped using a BTEQ script. If something goes wrong with an Update operator job, and you drop the target table manually and then try to rerun the job, you may lose the original data. This is because all rows are actually placed into worktables and they remain there until the Update operator job reaches the application phase, at which time the rows are copied to the real Target tables.