The single-pass upsert is described as atomic to emphasize that its component UPDATE and INSERT SQL statements are grouped together and performed as a single, or atomic, SQL request.
Existing Teradata Parallel Data Pump scripts that use the upsert feature in its Teradata Parallel Data Pump-specific form, using paired UPDATE and INSERT requests, do not have to be changed to take advantage of the atomic upsert capability because Teradata Parallel Data Pump automatically converts an UPDATE INSERT request pair in its older syntax into a corresponding atomic upsert request whenever appropriate.
The atomic upsert syntax can also be used by any CLIv2-based applications and is particularly useful when coded directly into BTEQ scripts.