Book Image

Apache Hive Cookbook

Book Image

Apache Hive Cookbook

Overview of this book

Hive was developed by Facebook and later open sourced in Apache community. Hive provides SQL like interface to run queries on Big Data frameworks. Hive provides SQL like syntax also called as HiveQL that includes all SQL capabilities like analytical functions which are the need of the hour in today’s Big Data world. This book provides you easy installation steps with different types of metastores supported by Hive. This book has simple and easy to learn recipes for configuring Hive clients and services. You would also learn different Hive optimizations including Partitions and Bucketing. The book also covers the source code explanation of latest Hive version. Hive Query Language is being used by other frameworks including spark. Towards the end you will cover integration of Hive with these frameworks.
Table of Contents (19 chapters)
Apache Hive Cookbook
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Preface
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...