Book Image

Mastering PostgreSQL 9.6

By : Hans-Jürgen Schönig
Book Image

Mastering PostgreSQL 9.6

By: Hans-Jürgen Schönig

Overview of this book

PostgreSQL is an open source database used for handling large datasets (Big Data) and as a JSON document database. It also has applications in the software and web domains. This book will enable you to build better PostgreSQL applications and administer databases more efficiently. We begin by explaining the advanced database design concepts in PostgreSQL 9.6, along with indexing and query optimization. You will also see how to work with event triggers and perform concurrent transactions and table partitioning, along with exploring SQL and server tuning. We will walk you through implementing advanced administrative tasks such as server maintenance and monitoring, replication, recovery and high availability, and much more. You will understand the common and not-so-common troubleshooting problems and how you can overcome them. By the end of this book, you will have an expert-level command of the advanced database functionalities and will be able to implement advanced administrative tasks with PostgreSQL.
Table of Contents (14 chapters)
Free Chapter
1
PostgreSQL Overview

Understanding PostgreSQL index types

So far only binary trees have been discussed. However, in many cases B-trees are just not enough. Why is that the case? As discussed in this chapter, B-trees are basically based on sorting. Operators <, <=, =, >= and > can be handled using B-trees. The trouble is: not all data types can be sorted in a useful way. Just imagine a polygon. How would you sort those objects in a useful way? Sure, you can sort by the area covered, its length or so, but doing that won't allow you to actually find them using a geometric search.

The solution to the problem is to provide more than just one index type. Each index will serve a special purpose and do exactly what is needed. The following index types are available (as of PostgreSQL 9.6):

test=# SELECT * FROM pg_am; 
amname | amhandler | amtype
--------+-------------+--------
btree | bthandler | i
hash | hashhandler...