You can enable rdd compression (*spark.rdd.compress*) also you can use MEMORY_ONLY_SER ( *sc.sequenceFile[String,String]("s3n://somebucket/part-00000").persist(StorageLevel.MEMORY_ONLY_SER* *)* ) to reduce the rdd size in memory.
Thanks Best Regards On Wed, Oct 22, 2014 at 7:51 PM, Darin McBeath <ddmcbe...@yahoo.com.invalid> wrote: > I have a PairRDD of type <String,String> which I persist to S3 (using the > following code). > > JavaPairRDD<Text, Text> aRDDWritable = aRDD.mapToPair(new > ConvertToWritableTypes()); > aRDDWritable.saveAsHadoopFile(outputFile, Text.class, Text.class, > SequenceFileOutputFormat.class); > > class ConvertToWritableTypes implements PairFunction<Tuple2<String, > String>, Text, Text> { > public Tuple2<Text, Text> call(Tuple2<String, String> record) { > return new Tuple2(new Text(record._1), new Text(record._2)); > > } > } > > When I look at the S3 reported size for say one of the parts (part-00000) > it indicates the size is 156MB. > > I then bring up a spark-shell and load this part-00000 and cache it. > > scala> val keyPair = > sc.sequenceFile[String,String]("s3n://somebucket/part-00000").cache() > > After execution an action for the above RDD to force the cache, I look at > the storage (using the Application UI) and it show that I'm using 297MB for > this RDD (when it was only 156MB in S3). I get that there could be some > differences between the serialized storage format and what is then used in > memory, but I'm curious as to whether I'm missing something and/or should > be doing things differently. > > Thanks. > > Darin. >