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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 bucket map join


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

A bucket map join is used when the tables are large and all the tables used in the join are bucketed on the join columns. In this type of join, one table should have buckets in multiples of the number of buckets in another table. For example, if one table has 2 buckets then the other table must have either 2 buckets or a multiple of 2 buckets (2, 4, 6, and so on). If the preceding condition is satisfied then the joining can be done at the mapper side only, otherwise a normal inner join is performed. This means that only the required buckets are fetched on the mapper side and not the complete table. That is, only the matching buckets of all small tables are replicated onto each mapper. Doing this, the efficiency of the query is improved drastically. In a bucket map join, data is not sorted.

Hive does not support a bucket map join by default. The following property needs to be set to true for the query...

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