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Mastering PostgreSQL 12

You're reading from   Mastering PostgreSQL 12 Advanced techniques to build and administer scalable and reliable PostgreSQL database applications

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Product type Paperback
Published in Nov 2019
Publisher Packt
ISBN-13 9781838988821
Length 470 pages
Edition 3rd Edition
Languages
Concepts
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Author (1):
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Hans-Jürgen Schönig Hans-Jürgen Schönig
Author Profile Icon Hans-Jürgen Schönig
Hans-Jürgen Schönig
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Toc

Table of Contents (18) Chapters Close

Preface 1. Section 1: Basic Overview
2. PostgreSQL 12 Overview FREE CHAPTER 3. Understanding Transactions and Locking 4. Section 2: Advanced Concepts
5. Making Use of Indexes 6. Handling Advanced SQL 7. Log Files and System Statistics 8. Optimizing Queries for Good Performance 9. Writing Stored Procedures 10. Managing PostgreSQL Security 11. Handling Backup and Recovery 12. Making Sense of Backups and Replication 13. Deciding on Useful Extensions 14. Troubleshooting PostgreSQL 15. Migrating to PostgreSQL 16. Assessment 17. Other Books You May Enjoy

Optimizing storage and managing cleanup

Transactions are an integral part of the PostgreSQL system. However, transactions come with a small price tag attached. As we've already shown in this chapter, sometimes, concurrent users will be presented with different data. Not everybody will get the same data returned by a query. In addition to this, DELETE and UPDATE are not allowed to actually overwrite data since ROLLBACK would not work. If you happen to be in the middle of a large DELETE operation, you cannot be sure whether you will be able to COMMIT or not. In addition to this, data is still visible while you perform DELETE, and sometimes data is even visible once your modification has long since finished.

Consequently, this means that cleanup has to happen asynchronously. A transaction cannot clean up its own mess and COMMIT/ROLLBACK might be too early to take care...

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