Book Image

Oracle Database 11gR2 Performance Tuning Cookbook

By : Ciro Fiorillo
Book Image

Oracle Database 11gR2 Performance Tuning Cookbook

By: Ciro Fiorillo

Overview of this book

Oracle's Database offers great performance, scalability, and many features for DBAs and developers. Due to a wide choice of technologies, successful applications are good candidates to run into performance issues and when a problem arises it's very difficult to identify the cause and the right solution to the problem. The Oracle Database 11g R2 Performance Tuning Cookbook helps DBAs and developers to understand every aspect of Oracle Database that can affect performance. You will be guided through implementing the correct solution in a proactive way before problems arise, and how to diagnose issues on your Oracle database-based solutions. This fast-paced book offers solutions starting from application design and development, through the implementation of well-performing applications, to the details of deployment and delivering best-performance databases. With this book you will quickly learn to apply the right methodology to tune the performance of an Oracle Database, and to optimize application design and SQL and PL/SQL code. By following the real-world examples you will see how to store your data in correct structures and access and manipulate them at a lightning speed. You will learn to speed up sort operations, hack the optimizer and the data loading process, and diagnose and tune memory, I/O, and contention issues. The purpose of this cookbook is to provide concise recipes, which will help you to build and maintain a very high-speed Oracle Database environment.
Table of Contents (21 chapters)
Oracle Database 11gR2 Performance Tuning Cookbook
Credits
About the Author
Acknowledgement
About the Reviewers
www.PacktPub.com
Preface
Index

Avoiding row chaining


We encounter row chaining when the size of the row data is larger than the size of the database block used to store it. In this situation, the row is split across more than one database block, so, to read it we need to access more than one database block, resulting in greater I/O.

Getting ready

Before we can start, we have to alter an initialization parameter of the test database (assuming the default block size is 8KB in the test database):

ALTER SYSTEM SET db_16k_cache_size = 16m scope=both;

We need to set this parameter to allocate a memory buffer dedicated to storing database blocks of a different size; in this recipe, we will create a tablespace using a 16KB block size, so we need the corresponding buffer allocated to use it.

How to do it...

In this recipe, we will examine how to detect row chaining issues, and how to avoid chaining in our tables. Follow these steps:

  1. Connect to the HR schema:

    CONNECT hr@TESTDB/hr
    
  2. Create the table BIG_ROWS:

    CREATE TABLE HR.BIG_ROWS ...