nathanmarz/cascalog — pull request #102 by ipostelnik (2012-12-10 22:33:37+00:00)
Title: Disable ability to create stateful mutligroup buffers

To fix #100, I've modified MultiGroupBy to not perform per-group prepare/cleanup. Unfortunately, the joiner doesn't have a good place to call code at start and end of the overall reduce. So the tradeoff is that multigroup buffers cannot be stateful.