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PostgreSQL 10 Administration Cookbook

You're reading from   PostgreSQL 10 Administration Cookbook Over 165 effective recipes for database management and maintenance in PostgreSQL 10

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Product type Paperback
Published in May 2018
Publisher Packt
ISBN-13 9781788474924
Length 576 pages
Edition 4th Edition
Languages
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Authors (2):
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Gianni Ciolli Gianni Ciolli
Author Profile Icon Gianni Ciolli
Gianni Ciolli
Simon Riggs Simon Riggs
Author Profile Icon Simon Riggs
Simon Riggs
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Toc

Table of Contents (14) Chapters Close

Preface 1. First Steps FREE CHAPTER 2. Exploring the Database 3. Configuration 4. Server Control 5. Tables and Data 6. Security 7. Database Administration 8. Monitoring and Diagnosis 9. Regular Maintenance 10. Performance and Concurrency 11. Backup and Recovery 12. Replication and Upgrades 13. Other Books You May Enjoy

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...

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