April 2016
Beginner
268 pages
5h 32m
English
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Chapter 7. Joins and Join Optimization
In this chapter, you will learn:
- Understanding the joins concept
- Using a left/right/full outer join
- Using a left semi join
- Using a cross join
- Using a map-side join
- Using a bucket map join
- Using a bucket sort merge map join
- Using a skew join
Understanding the joins concept
A join in Hive is used for the same purpose as in a traditional RDBMS. A join is used to fetch meaningful data from two or more tables based on a common value or field. In other words, a join is used to combine data from multiple tables. A join is performed whenever multiple tables are specified inside the FROM clause.
As of now, joins based on equality conditions only are supported in Hive. It does not support any join condition that is based on non-equality ...
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