yes this was my understanding also but then i found that Spark's DataFrame does has a method which appends to Parquet ( df.write.parquet(destName, mode="append")). below is an article that throws some light on this. i was wondering if there is a way to achieve the same through NiFi.
http://aseigneurin.github.io/2017/03/14/incrementally-loaded-parquet-files.html I have a workaround in mind for this where i can save data i want to append to parque in a file (say in avro format) and then execute a script through ExecuteProcess to launch a spark job to read avro and append to an existing Parquet file and then delete avro. I am looking for a simpler way than this. -- Sent from: http://apache-nifi-developer-list.39713.n7.nabble.com/
