Cascalog
Cascalog is a fully-featured data processing and querying library for Clojure or Java. The main use cases for Cascalog are processing "Big Data" on top of Hadoop or doing analysis on your local computer. Cascalog is a replacement for tools like Pig, Hive, and Cascading and operates at a significantly higher level of abstraction than those tools.
Follow the getting started steps, check out the tutorial, and you'll be running Cascalog queries on your local computer within 5 minutes.
Getting Started with JCascalog
To get started with JCascalog, Cascalog's pure-Java API, see this wiki page. The jcascalog.Playground class has in-memory datasets that you can play with to learn the basics.
Latest Version
The latest release version of Cascalog is hosted on Clojars:
Getting started with Clojure Cascalog
The best way to get started with Cascalog is experiment with the toy datasets that ship with the project. These datasets are served from memory and can be played with purely from the REPL. Just follow these steps and you'll be on your way:
- Install leiningen
- Make sure you have Java 1.6 (run
java -version) - Start a new leiningen project with
lein new <project name>, replacing<project name> - Include dependency on Cascalog in your project by adding
[cascalog/cascalog-core "2.1.0"]into your project'sproject.cljfile. - Work through the examples in the Getting Started Guide.
Using Cascalog within a project
Cascalog is hosted at Clojars, and some of its dependencies are hosted at Conjars. Both Clo/Con-jars are maven repos that's easy to use with maven or leiningen.
To include Cascalog in your leiningen or cake project, add the following to your project.clj:
General
[cascalog/cascalog-core "3.0.0"] ;; under :dependencies
[org.apache.hadoop/hadoop-core "1.2.1"] ;; under :dev-dependencies
Leiningen 2.0
:repositories {"conjars" "http://conjars.org/repo"}
:dependencies [cascalog/cascalog-core "3.0.0"]
:profiles { :provided {:dependencies [[org.apache.hadoop/hadoop-core "1.2.1"]]}}
Leiningen < 2.0
:dependencies [cascalog/cascalog-core "3.0.0"]
:dev-dependencies [[org.apache.hadoop/hadoop-core "1.2.1"]]
Note that Cascalog is compatible with Clojure 1.2.0, 1.2.1, 1.3.0, 1.4.0, and 1.5.1.
Documentation and Issue Tracker
- The Cascalog website contains more information and links to Various articles and tutorials.
- API documentation can be found at http://nathanmarz.github.io/cascalog/.
- Issue Tracker on Github.
Come chat with us in the Google group: cascalog-user
Or in the #cascalog or #cascading rooms on freenode!
Priorities for Cascalog development
- Replicated and bloom joins
- Cross query optimization: push constants and filters down into subqueries when possible
Acknowledgements
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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.