Github user marmbrus commented on the pull request:
https://github.com/apache/spark/pull/482#issuecomment-41227747
I'm not sure if we want to overload the nullability interface in this way.
This nullability bit currently is mostly intended for use when determining
storage layout of tuples (i.e. do we need to keep a null bit around or can we
operate on primitives). What is going on here is something like constraint
propagation + null domination, which we might be able to accomplish more
generally.
Also, I'm not sure if its a good idea to provide a default implementation
of nullability as there are quite a few operators whose nullability isn't
defined by their children (many aggregate operators for example).
Perhaps there is a simpler way to do this using an improved rule in the
optimizer.
---
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 [email protected] or file a JIRA ticket
with INFRA.
---
