On Fri, Dec 5, 2014 at 7:12 AM, Tobias Pfeiffer <tgp@preferred.jp> wrote:
Rahul,

On Fri, Dec 5, 2014 at 2:50 PM, Rahul Bindlish <rahul.bindlish@nectechnologies.in> wrote:
I have done so thats why spark is able to load objectfile [e.g. person_obj]
and spark has maintained serialVersionUID [person_obj].

Next time when I am trying to load another objectfile [e.g. office_obj] and
I think spark is matching serialVersionUID [person_obj] with previous
serialVersionUID [person_obj] and giving mismatch error.

In my first post, I have give statements which can be executed easily to
replicate this issue.

Can you post the Scala source for your case classes? I have tried the following in spark-shell:

case class Dog(name: String)
case class Cat(age: Int)
val dogs = sc.parallelize(Dog("foo") :: Dog("bar") :: Nil)
val cats = sc.parallelize(Cat(1) :: Cat(2) :: Nil)
dogs.saveAsObjectFile("test_dogs")
cats.saveAsObjectFile("test_cats")

This gives two directories "test_dogs/" and "test_cats/". Then I restarted spark-shell and entered:

case class Dog(name: String)
case class Cat(age: Int)
val dogs = sc.objectFile("test_dogs")
val cats = sc.objectFile("test_cats")

I don't get an exception, but:

dogs: org.apache.spark.rdd.RDD[Nothing] = FlatMappedRDD[1] at objectFile at <console>:12

You need to specify the type of the RDD. The compiler does not know what is in "test_dogs".

val dogs = sc.objectFile[Dog]("test_dogs")
val cats = sc.objectFile[Cat]("test_cats")

It's an easy mistake to make... I wonder if an assertion could be implemented that makes sure the type parameter is present.