What formats can Amazon EMR return?

The default output format for a cluster is text with key, value pairs written to individual lines of the text files. This is the output format most commonly used.

If your output data needs to be written in a format other than the default text files, you can use the Hadoop interface OutputFormat to specify other output types. You can even create a subclass of the FileOutputFormat class to handle custom data types. For more information, see http://hadoop.apache.org/docs/current/api/org/apache/hadoop/mapred/OutputFormat.html.

If you are launching a Hive cluster, you can use a serializer/deserializer (SerDe) to output data from HDFS to a given format. For more information, see https://cwiki.apache.org/confluence/display/Hive/SerDe.