You asked it to fetch a batch (15min) then iterated over the batch (all at once). To stream, fetch more batches. What ddb does to get the batches depends on h

You asked it to fetch a batch (15min) then iterated over the batch (all at once). To stream, fetch more batches. What ddb does to get the batches depends on hand wavey magic around available ram, and also the structure of the parquet.