Book Image

PostgreSQL 10 Administration Cookbook - Fourth Edition

By : Simon Riggs, Gianni Ciolli
Book Image

PostgreSQL 10 Administration Cookbook - Fourth Edition

By: Simon Riggs, Gianni Ciolli

Overview of this book

PostgreSQL is a powerful, open source database management system with an enviable reputation for high performance and stability. With many new features in its arsenal, PostgreSQL 10 allows users to scale up their PostgreSQL infrastructure. This book takes a step-by-step, recipe-based approach to effective PostgreSQL administration. Throughout this book, you will be introduced to these new features such as logical replication, native table partitioning, additional query parallelism, and much more. You will learn how to tackle a variety of problems that are basically the pain points for any database administrator - from creating tables to managing views, from improving performance to securing your database. More importantly, the book pays special attention to topics such as monitoring roles, backup, and recovery of your PostgreSQL 10 database, ensuring high availability, concurrency, and replication. By the end of this book, you will know everything you need to know to be the go-to PostgreSQL expert in your organization.
Table of Contents (14 chapters)

Randomly sampling data

DBAs may be asked to set up a test server and populate it with test data. Often, that server will be old hardware, possibly with smaller disk sizes. So, the subject of data sampling raises its head.

The purpose of sampling is to reduce the size of the dataset and improve the speed of later analysis. Some statisticians are so used to the idea of sampling that they may not even question whether its use is valid or it can cause further complications.

The SQL standard way to perform sampling is by adding the TABLESAMPLE clause to the SELECT statement.

How to do it...

In this section, we will take a random sample of a given collection of data (for example, a given table). First, you should realize that there...