Spark dataframe to collect

Which implementation to use while collecting Spark dataframe - row-wise: fetch the entire dataframe into memory and then process it row-by-row - row-wise-iter: iterate through the dataframe using RDD local iterator, processing one row at a time (hence reducing memory footprint) - column-wise: fetch the entire dataframe into memory and then process it column-by-column NOTE: (1) this will not apply to streaming or arrow use cases (2) this parameter will only affect implementation detail, and will not affect result of 'sdf_collect', and should only be set if performance profiling indicates any particular choice will be significantly better than the default choice ("row-wise")

Additional options.