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Mastering PostgreSQL 15

Mastering PostgreSQL 15

By : Hans-Jürgen Schönig
4.9 (7)
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Mastering PostgreSQL 15

Mastering PostgreSQL 15

4.9 (7)
By: Hans-Jürgen Schönig

Overview of this book

Starting with an introduction to the newly released features of PostgreSQL 15, this updated fifth edition will help you get to grips with PostgreSQL administration and how to build dynamic database solutions for enterprise apps, including designing both physical and technical aspects of the system. You'll explore advanced PostgreSQL features, such as logical replication, database clusters, advanced indexing, and user management to manage and maintain your database. You'll then work with the PostgreSQL optimizer, configure PostgreSQL for high speed, and move from Oracle to PostgreSQL. Among the other skills that the book will help you build, you’ll cover transactions, handling recursions, working with JSON and JSONB data, and setting up a Patroni cluster. It will show you how to improve performance with query optimization. You'll also focus on managing network security and work with backups and replication while exploring useful PostgreSQL extensions that optimize the performance of large databases. By the end of this PostgreSQL book, you’ll be able to use your database to its utmost capacity by implementing advanced administrative tasks with ease.
Table of Contents (16 chapters)
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Writing your own aggregates

In this book, you will learn about most of the built-in functions provided by PostgreSQL. However, what SQL provides might not be enough for you. The good news is that it is possible to add your own aggregates to the database engine. In this section, you will learn how that can be done.

Creating simple aggregates

For this example, the goal is to solve a very simple problem. If a customer takes a taxi, they usually have to pay for getting in the taxi—for example, €2.50. Now, let’s assume that for each kilometer, the customer has to pay €2.20. The question now is, what is the total price of a trip?

Of course, this example is simple enough to solve without a custom aggregate; however, let’s see how it works. First, some test data needs to be created:

test=# CREATE TABLE t_taxi (trip_id int, km numeric);
CREATE TABLE
test=# INSERT INTO t_taxi
  VALUES (1, 4.0), (1, 3.2), (1, 4.5), (2, 1.9), (2, 4.5);
INSERT...

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