apache spark - How to get an Iterator of Rows using Dataframe in SparkSQL

Question

I have an application in SparkSQL which returns large number of rows that are very difficult to fit in memory so I will not be able to use collect function on DataFrame, is there a way using which I can get all this rows as an Iterable instaed of the entire rows as list.

I am executing this SparkSQL application using yarn-client.

Answer 1

Generally speaking transferring all the data to the driver looks a pretty bad idea and most of the time there is a better solution out there but if you really want to go with this you can use toLocalIterator method on a RDD:

val df: org.apache.spark.sql.DataFrame = ???
df.cache // Optional, to avoid repeated computation, see docs for details
val iter: Iterator[org.apache.spark.sql.Row]  = df.rdd.toLocalIterator