[Investigate] Why does writing MeterValues Request take 32 seconds and others take 2 seconds?

[kelseymok]

In the Batch Processing Silver layer exercise, writing MeterValues request to parquet (single partition) takes 32 seconds... whereas writing all of the other DFs for other actions takes sub 2 seconds. Why is that?

NOTE: to run this exercise, please run the Bronze exercise - it outputs some parquet which the SIlver Exercise requires.