Book Image

Learn PostgreSQL

By : Luca Ferrari, Enrico Pirozzi
Book Image

Learn PostgreSQL

By: Luca Ferrari, Enrico Pirozzi

Overview of this book

PostgreSQL is one of the fastest-growing open source object-relational database management systems (DBMS) in the world. As well as being easy to use, it’s scalable and highly efficient. In this book, you’ll explore PostgreSQL 12 and 13 and learn how to build database solutions using it. Complete with hands-on tutorials, this guide will teach you how to achieve the right database design required for a reliable environment. You'll learn how to install and configure a PostgreSQL server and even manage users and connections. The book then progresses to key concepts of relational databases, before taking you through the Data Definition Language (DDL) and commonly used DDL commands. To build on your skills, you’ll understand how to interact with the live cluster, create database objects, and use tools to connect to the live cluster. You’ll then get to grips with creating tables, building indexes, and designing your database schema. Later, you'll explore the Data Manipulation Language (DML) and server-side programming capabilities of PostgreSQL using PL/pgSQL, before learning how to monitor, test, and troubleshoot your database application to ensure high-performance and reliability. By the end of this book, you'll be well-versed with the Postgres database and be able to set up your own PostgreSQL instance and use it to build robust solutions.
Table of Contents (27 chapters)
1
Section 1: Getting Started
5
Section 2: Interacting with the Database
12
Section 3: Administering the Cluster
20
Section 4: Replication
23
Section 5: The PostegreSQL Ecosystem

Savepoints

A savepoint is a way to split a transaction into smaller blocks that can be rolled back independently of each other. Thanks to savepoints, you can divide a big transaction (one transaction with multiple statements) into smaller chunks, allowing a subset of the bigger transaction to fail without having the overall transaction fail. PostgreSQL does not handle transaction nesting, so you cannot issue a nested set of BEGIN, nor COMMIT/ROLLBACK statements. Savepoints allow PostgreSQL to mimic the nesting of transaction blocks.

Savepoints are marked with a mnemonic name, which you can use to commit or rollback. The name must be unique within the transaction, and if you reuse the same over and over, the previous savepoints with the same name will be discarded. Let's see an example:

forumdb=> BEGIN;
BEGIN
forumdb=> INSERT INTO tags( tag ) VALUES ( 'Eclipse IDE' );
INSERT 0 1
forumdb=> SAVEPOINT other_tags;
SAVEPOINT
forumdb=> INSERT INTO tags( tag ) VALUES ( &apos...