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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hive/GenericUDAFCaseStudy" by JohnSichi
Date Mon, 23 Aug 2010 17:56:59 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "Hive/GenericUDAFCaseStudy" page has been changed by JohnSichi.
http://wiki.apache.org/hadoop/Hive/GenericUDAFCaseStudy?action=diff&rev1=4&rev2=5

--------------------------------------------------

  
  This tutorial walks through the development of the `histogram()` UDAF, which computes a
histogram with a fixed, user-specified number of bins, using a constant amount of memory and
time linear in the input size. It demonstrates a number of features of Generic UDAFs, such
as a complex return type (an array of structures), and type checking on the input. The assumption
is that the reader wants to write a UDAF for eventual submission to the Hive open-source project,
so steps such as modifying the function registry in Hive and writing `.q` tests are also included.
If you just want to write a UDAF, debug and deploy locally, see [[http://wiki.apache.org/hadoop/Hive/HivePlugins
| this page]].
  
- '''NOTE:''' In this tutorial, we walk through the creation of a `histogram()` function.
In future (as of July 2010) releases of Hive, this will appear as the built-in function `histogram_numeric()`.
+ '''NOTE:''' In this tutorial, we walk through the creation of a `histogram()` function.
In upcoming releases of Hive, this will appear as the built-in function `histogram_numeric()`.
  
  <<TableOfContents(3)>>
  

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