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Apache Hive Cookbook

Apache Hive Cookbook

By : Hanish Bansal, Saurabh Chauhan, Shrey Mehrotra
3 (4)
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Apache Hive Cookbook

Apache Hive Cookbook

3 (4)
By: Hanish Bansal, Saurabh Chauhan, Shrey Mehrotra

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 (14 chapters)
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13
Index

Using a cross join


In this recipe, you will learn how to use a cross join in Hive.

Cross join, also known as Cartesian product, is a way of joining multiple tables in which all the rows or tuples from one table are paired with the rows and tuples from another table. For example, if the left-hand side table has 10 rows and the right-hand side table has 13 rows then the result set after joining the two tables will be 130 rows. That means all the rows from the left-hand side table (having 10 rows) are paired with all the tables from the right-hand side table (having 13 rows).

If there is a WHERE clause in the SQL statement that includes a cross join, then first the cross join takes place and then the result set is filtered out with the help of the WHERE clause. This means cross joins are not an efficient and optimized way of joining the tables.

The general syntax of a cross join is as follows:

join_condition
  | table_reference [CROSS] JOIN table_reference join_condition

Where:

  • table_reference: Is...

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