[GitHub] spark pull request: [SPARK-11416][BUILD] Update to Chill 0.8.0 & K...

[steveloughran <gi...@git.apache.org>]

Github user steveloughran commented on the pull request:

    https://github.com/apache/spark/pull/12076#issuecomment-204324891
  
    1. Hive uses Kryo "the guava of serialization" internally; I don't know the specifics, but its not insignificant.
    1. they moved ahead of spark's version to fix some bugs; that's the kryo which repackaged things. 
    1. Kryo types were used across methods called from Spark; the unshading was needed to get things to link, same with the switch from 2.22 to 2.21 (and a change to some files). It was less traumatic to push Hive back slightly than to try to force an update into unknown territory for chill & dependencies, even if it were possible.
    
    Upgrading to hive 2 would finally get everything in sync: ideally eliminate the need to have a custom hive JAR at all. Essentially all spark needs is a version of Hive with parameters that can be exchanged across all needed methods, with the conflict packages shaded, and the non-conflict packages generally omitted
    
    If you want to find out where things don't link, edit the spark pom to pull in org.apache.hive/hive and see what breaks.
    
    
    (of course, the other thing that would be nice would be for Hive to make it possible to subclass their thrift service cleanly; I've got a PoC of that somewhere ... it's not hard to add)


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