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
PostgreSQL Overview

Improving speed using clustered tables

In this section, you will learn about the power of correlation and the power of clustered tables. What is the whole idea? Consider you want to read a whole area of data. This might be a certain time range, some block, IDs, or so. The runtime of such queries will vary depending on the amount of data and the physical arrangement of data on disk. So, even if you are running queries that return the same number of rows, two systems might not provide the answer within the same time span as a physical disk layout might make a difference.

Here is an example:

test=# EXPLAIN (analyze true, buffers true, timing true)
FROM t_test
WHERE id < 10000;
Index Scan using idx_id on t_test (cost=0.43..370.87 rows=10768 width...