Book Image

PostgreSQL 9 Admin Cookbook

By : Simon Riggs, Hannu Krosing
Book Image

PostgreSQL 9 Admin Cookbook

By: Simon Riggs, Hannu Krosing

Overview of this book

<p>PostgreSQL is a powerful, open source object-relational database system. An enterprise database, PostgreSQL includes features such as Multi-Version Concurrency Control (MVCC), point-in-time recovery, tablespaces, asynchronous replication, nested transactions (savepoints), online/hot backups, a sophisticated query planner/optimizer, and write-ahead logging for fault tolerance. PostgreSQL 9 Admin cookbook covers everything a database administrator needs to protect, manage and run a healthy and efficient PostgreSQL 9.0 database.</p> <p>PostgreSQL 9 Admin Cookbook describes key aspects of the PostgreSQL open source database system. The book covers everything a sysadmin or DBA needs to protect, manage, and run a healthy and efficient PostgreSQL 9 database. This hands-on guide will assist developers working on live databases, supporting web or enterprise software applications using Java, Python, Ruby, or .Net from any development framework. It's easy to manage your database when you've got PostgreSQL 9 Admin Cookbook to hand.</p> <p>PostgreSQL is fast becoming one of the world's most popular server databases with an enviable reputation for performance, stability, and an enormous range of advanced features. PostgreSQL is one of the oldest open source projects, completely free to use and developed by a very diverse worldwide community. Most of all, It Just Works!</p> <p>PostgreSQL 9 Admin Cookbook offers the information you need to manage your live production databases on PostgreSQL. The book contains insights direct from the main author of the PostgreSQL replication and recovery features, and the database architect of the most successful startup using PostgreSQL, Skype.</p> <p>This practical guide gives quick answers to common questions and problems, building on the authors' experience as trainers, users, and core developers of the PostgreSQL database server.</p> <p>Each technical aspect is broken down into short recipes that demonstrate solutions with working code then explain why and how that works. The book is intended to be a desk reference for both new users and technical experts.</p> <p>The book covers all the latest features in PostgreSQL 9. Soon you will be running a smooth database with ease!</p>
Table of Contents (18 chapters)
PostgreSQL 9 Administration Cookbook
Credits
About the Authors
About the Reviewers
Preface
Index

Finding slow SQL statements


There are two main kinds of slowness which can manifest themselves in a database.

The first kind is a single query that can be too slow to be really useable, such as a customer information query in a CRM running for minutes, a password check query running in tens of seconds, or a daily data-aggregation query running for more than a day. These can be found by logging queries that take over a certain amount of time, either at the client end, or in the database.

The second kind is a query that is run frequently (say a few thousand times a second), and which used to run in single digit milliseconds, but now is running in several tens or even hundreds of milliseconds, and is slowing down the system. This kind of slowness is much harder to find.

Here, we will show several ways to find the statements that are either slow, or although not being slow by themselves, cause the database as a whole to slow down.

Getting ready

Connect to the database as the user whose statements...