DataSet save to parquet partition problem

[Junfeng Chen]

I am trying to save a DataSet<Row> object to parquet file via

> df.write().partitionBy("...").parquet(path)


while this dataset contains the following struct:
time: struct
    -dayOfMonth
    -monthOfYear
    ...

Can I use the child field like time.monthOfYear as above in partition ? If
yes, how？

Thanks！

Regard,
Junfeng Chen