When you create a mass ingestion specification, run an initial full load before you begin running incremental loads on the data. The initial full load allows the Spark engine to create a basis to fetch incremental data in subsequent runs.
An initial full load can also help administrators maintain self-documented records. For example, it is possible to run an incremental load using overwrite mode as the first run of the specification, but the Spark engine does not have a basis to fetch incremental data. As a result, the Spark engine ingests all of the data from the source and effectively runs a full load. The records would indicate that a user ran an incremental load, but it might be unclear whether all data or only incremental data was ingested to the target.
If you run a initial full load followed by subsequent incremental loads, the administrator can distinguish whether the Spark engine ingested all data or only incremental data for each run of the specification.