What is newDS? If it is a Streaming Dataset/DataFrame (since you have writeStream there) then there seems to be an issue preventing toJSON to work.
________________________________ From: kant kodali <kanth...@gmail.com> Sent: Saturday, September 9, 2017 4:04:33 PM To: user @spark Subject: Queries with streaming sources must be executed with writeStream.start() Hi All, I have the following code and I am not sure what's wrong with it? I cannot call dataset.toJSON() (which returns a DataSet) ? I am using spark 2.2.0 so I am wondering if there is any work around? Dataset<String> ds = newDS.toJSON().map(()->{some function that returns a string}); StreamingQuery query = ds.writeStream().start(); query.awaitTermination();