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Apache Hive Essentials - Second Edition
book

Apache Hive Essentials - Second Edition

by Dayong Du
June 2018
Beginner to intermediate content levelBeginner to intermediate
210 pages
5h 12m
English
Packt Publishing
Content preview from Apache Hive Essentials - Second Edition

Basic aggregation 

Data aggregation is the process of gathering and expressing data in a summary to get more information about particular groups based on specific conditions. HQL offers several built-in aggregate functions, such as max(...), min(...), and avg(...). It also supports advanced aggregation using keywords such as GROUPING SETS, ROLLUP, and CUBE, and different types of window function.

The basic built-in aggregate functions are usually used with the GROUP BY clause. If there is no GROUP BY clause specified, it aggregates over the whole row (all columns) by default. Besides aggregate functions, all columns selected must also be included in the GROUP BY clause. The following are a few examples involving the built-in aggregate functions: ...

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Publisher Resources

ISBN: 9781788995092Supplemental Content