apache/spark — pull request #2519 by ash211 (2014-09-24 08:56:01+00:00)
Title: SPARK-3526 Add section about data locality to the tuning guide

cc @kayousterhout

I have a few outstanding questions from compiling this documentation:
- What's the difference between NO_PREF and ANY? I understand the implications of the ordering but don't know what an example of each would be
- Why is NO_PREF ahead of RACK_LOCAL? I would think it'd be better to schedule rack-local tasks ahead of no preference if you could only do one or the other. Is the idea to wait longer and hope for the rack-local tasks to turn into node-local or better?
- Will there be a datacenter-local locality level in the future? Apache Cassandra for example has this level