Github user kanzhang commented on the pull request:
https://github.com/apache/spark/pull/829#issuecomment-44921900
@marmbrus you are probably right.
I didn't realize ```cachedColumnBuffers``` are themself RDDs and was
thinking in the wrong direction.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
