There are a number of custom analytics approaches that have been used at Twitter. One of the authors of the Summingbird framework, Sam Ritchie - has also worked on Cascalog (Clojure mapreduce library).
You can see a presentation about a Clojure solution in Cascalog to a similar set of problems by Sam Ritchie here: "Cascalog 2 - Streaming MapReduce in Clojure" https://speakerdeck.com/sritchie/cascalog-2-dot-0-datalog-in...