Book Image

PostgreSQL Development Essentials

By : Manpreet Kaur, Baji Shaik
Book Image

PostgreSQL Development Essentials

By: Manpreet Kaur, Baji Shaik

Overview of this book

PostgreSQL is the most advanced open source database in the world. It is easy to install, configure, and maintain by following the documentation; however, it’s difficult to develop applications using programming languages and design databases accordingly. This book is what you need to get the most out of PostgreSQL You will begin with advanced SQL topics such as views, materialized views, and cursors, and learn about performing data type conversions. You will then perform trigger operations and use trigger functions in PostgreSQL. Next we walk through data modeling, normalization concepts, and the effect of transactions and locking on the database. The next half of the book covers the types of indexes, constrains, and the concepts of table partitioning, as well as the different mechanisms and approaches available to write efficient queries or code. Later, we explore PostgreSQL Extensions and Large Object Support in PostgreSQL. Finally, you will perform database operations in PostgreSQL using PHP and Java. By the end of this book, you will have mastered all the aspects of PostgreSQL development. You will be able to build efficient enterprise-grade applications with PostgreSQL by making use of these concepts
Table of Contents (17 chapters)
PostgreSQL Development Essentials
About the Authors
About the Reviewers

Clustering on an index

PostgreSQL supports clustering a table using an index. CLUSTER is used to do that. What does it do? It reorganizes the table based on the index. Why do we need it? It can greatly increase performance when you query a range of index values or a single index value with multiple entries because the queried data is in one place on the disk.

The syntax is as follows:

CLUSTER [VERBOSE] table_name [ USING index_name ]

Here's an example of how to create a cluster and how it improves the performance:

CREATE TABLE table_cluster(
  id integer,
name varchar);
INSERT INTO table_cluster VALUES(generate_series(1,10000000), 'test_name'||generate_series(1,10000000));
CREATE INDEX table_cluster_idx ON table_cluster(id);

Query the table in such way that the index is used and look at the execution time. The following is an example:

postgres=# EXPLAIN ANALYZE SELECT * FROM table_cluster WHERE id  BETWEEN 10000 AND 200000;
                  QUERY PLAN