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Apache Hive Cookbook

You're reading from   Apache Hive Cookbook

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Product type Paperback
Published in Apr 2016
Publisher Packt
ISBN-13 9781782161080
Length 268 pages
Edition 1st Edition
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Toc

Table of Contents (14) Chapters Close

Preface 1. Developing Hive 2. Services in Hive FREE CHAPTER 3. Understanding the Hive Data Model 4. Hive Data Definition Language 5. Hive Data Manipulation Language 6. Hive Extensibility Features 7. Joins and Join Optimization 8. Statistics in Hive 9. Functions in Hive 10. Hive Tuning 11. Hive Security 12. Hive Integration with Other Frameworks Index

Exploring views


Views in SQL provide abstraction from querying a table directly. A view could be a combination of multiple tables joined or grouped on a set of columns. In RDBMS, views could be broadly categorized into two types:

  • Materialized views

  • Non-materialized views

Hive supports only non-materialized views and as it does not support materialized data, the view is strictly bound to the tables it is based on. In other words, it also means if the columns of the tables are altered or dropped, it would affect the view or even fail the view.

How to do it…

These views are the logical constructs that do not store data with them. When a view is created in Hive, the underlying query is stored in the metastore. When the view is queried, the view's clauses or conditions are evaluated before the underlying query clause. For example, if the query has a limit of 200 and the view has a limit of 100 then the query would return 100 results.

An example of a view definition is as follows:

CREATE VIEW sales_view...
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