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

Using the built-in User Defined Table Function (UDTF)


Normal functions take one row as input and provide one row as transformed output. On the other side, built-in table-generating functions take one row as input and produce multiple output rows.

How to do it…

The built-in table-generating functions could be used directly in the query. The following are some examples of the table-generating functions available in Hive:

Function Name

Return Type

Description

explode(ARRAY)

N rows

It will return n of rows where n is the size of an array. This function represents each element of an array as a row.

explode(MAP)

N rows

It will return n number of rows where n is the size of a map. This function represents each key-value element of the map as a row containing two columns: one for key and another for value.

inline(ARRAY<STRUCT[,STRUCT]>)

 

It is used to explode an array of struct elements into a table.

json_tuple(jsonStr, k1, k2, ...)

tuple

It is used to extract a set of keys from...