Book Image

Apache Hive Essentials

By : Dayong Du
Book Image

Apache Hive Essentials

By: Dayong Du

Overview of this book

Table of Contents (17 chapters)
Apache Hive Essentials
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Analytic functions


Analytic functions, available since Hive 0.11.0, are a special group of functions that scan the multiple input rows to compute each output value. Analytic functions are usually used with OVER, PARTITION BY, ORDER BY, and the windowing specification. Different from the regular aggregate functions used with the GROUP BY clause that is limited to one result value per group, analytic functions operate on windows where the input rows are ordered and grouped using flexible conditions expressed through an OVER PARTITION clause. Though analytic functions give aggregate results, they do not group the result set. They return the group value multiple times with each record. The analytic functions offer great flexibility and functionalities than the regular GROUP BY clause and make special aggregations in Hive easier and powerful. The syntax for the analyze function is as follows:

Function (arg1,..., argn) OVER ([PARTITION BY <...>] [ORDER BY <....>] [<window_clause...