Cascalog is a tool for processing data on Hadoop with Clojure in a concise and expressive manner. Cascalog combines two cutting edge technologies in Clojure and Hadoop and resurrects an old one in Datalog. Cascalog is high performance, flexible, and robust.
Most query languages, like SQL, Pig, and Hive, are custom languages -- and this leads to huge amounts of accidental complexity. Constructing queries dynamically by doing string manipulation is an impedance mismatch and makes usual programming techniques like abstraction and composition difficult.
Cascalog queries are first-class within Clojure and are extremely composable. Additionally, the Datalog syntax of Cascalog is simpler and more expressive than SQL-based languages.
Follow the getting started steps, check out the tutorial, and you'll be running Cascalog queries on your local computer within 5 minutes.
Documentation and issue tracker can be found on the Cascalog wiki
Google group: cascalog-user
Come chat in the #cascading room on freenode
Cascalog is hosted at Clojars. Clojars is a maven repo that is trivially easy to use with maven or leiningen.
- Replicated and bloom joins
- Cross query optimization: push constants and filters down into subqueries when possible
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Cascalog is based off of a very early branch of cascading-clojure project (http://github.com/clj-sys/cascading-clojure). Special thanks to Bradford Cross and Mark McGranaghan for their work on that project. Much of that code appears within Cascalog in either its original form or a modified form.