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Complex data manipulation in Cascalog, Pig, and Hive

Bruno Bonacci brings up some very good points why using a single and coherent solution to manipulate data results in higher productivity by comparing what Pig and Hive require:

In languages like Pig and Hive, in order to make complex manipulation of your data you have to write User Defined Functions (UDF). UDFs are a great way to extend the basic functionality, however for Hive and Pig you have to use a different language to write your UDFs as the basic SQL or Pig Latin languages have only a handful of functions and they lack of basic control structures. Both they offer the possibility to write UDFs in a number of different languages (which is great), however this requires a programming paradigm switch by the developer. Pig allows to write UDFs in Java, Jython, JavaScript, Groovy, Ruby and Python, for Hive you need to write then in Java (good article here). I won’t make the example of UDFs in Java as the comparison won’t be fair, life is too short to write them in Java, but let’s assume that you want to write a UDF for Pig and you want to use Python. If you go for the JVM platform version (Jython) you won’t be able to use existing modules coming from Python ecosystem (unless they are in pure Python). Same for Ruby and Javascript. If you decide to use Python you will have the setup burden of installing Python and all the modules that you intend to use in every Hadoop task node. So, you start with a language such as Pig Latin or SQL, you have to write, compile and bundle UDFs in a different language, you are constrained to use only the plain language without importing modules or face the extra burden of additional setup and, as if is not enough, you have to smooth the type difference between the two languages during their communication back and forth with the UDF. For me that’s enough to say that we can do better than that. Cascalog is a Clojure DSL, so your main language is Clojure, your custom functions are Clojure, the data are represented in Clojure data types, and the runtime is the JVM, no-switch required, no additional compilation required, no installation burden, and you can use all available libraries in the JVM ecosystem.

I’m not a big fan of SQL, except the cases where it really belongs to; SQL-on-Hadoop is my least favorite topic, probably except the whole complexity of the ecosystem. In the space of multi-format/unstructured data I’ve always liked the pragmatism and legibility of Pig. But the OP is definitely right about the added complexity.

This also reminded me about the Python vs R “war”.

Original title and link: Complex data manipulation in Cascalog, Pig, and Hive (NoSQL database©myNoSQL)

via: http://blog.brunobonacci.com/2014/06/01/cascalog-by-examples-part1/