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Data processing on Hadoop without the hassle.
Clojure Java Shell

Merge pull request #283 from ipostelnik/filter-nulls

Use FilterNull to enforce ?var filtering
latest commit ba49f30947
@sritchie sritchie authored


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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:

Current Version

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:

  1. Install leiningen
  2. Make sure you have Java 1.6 (run java -version)
  3. Start a new leiningen project with lein new <project name>, replacing <project name>
  4. Include dependency on Cascalog in your project by adding [cascalog/cascalog-core "2.1.0"] into your project's project.clj file.
  5. 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:


[cascalog/cascalog-core "2.1.1"] ;; under :dependencies
[org.apache.hadoop/hadoop-core "1.2.1"] ;; under :dev-dependencies

Leiningen 2.0

:repositories {"conjars" ""}
:dependencies [cascalog/cascalog-core "2.1.1"]
:profiles { :provided {:dependencies [[org.apache.hadoop/hadoop-core "1.2.1"]]}}

Leiningen < 2.0

:dependencies [cascalog/cascalog-core "2.1.1"]
: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

Come chat with us in the Google group: cascalog-user

Or in the #cascalog or #cascading rooms on freenode!

Priorities for Cascalog development

  1. Replicated and bloom joins
  2. 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 ( 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.

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