With every cool new technology, people get overly infatuated and start using it for the wrong things. For example: Looking through a bazillion records for a few million marked with a set of criteria is a rather stupid use of MapReduce or your favorite DAG implementation (see: Spark).
For that and similar tasks, don’t forget the original big data technology: search. With great open source tools like Solr, Lucidworks, and Elasticsearch, you have a powerful way to optimize your I/O and personalize your user experience. It’s much better than holding fancy new tools from the wrong end.
