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

Using hash clusters


In the previous recipe, we introduced index clusters and tested a particular way to load data in a cluster to optimize the storage of rows with the same cluster key value.

In this recipe, we introduce a different kind of cluster—hash clusters. The biggest difference between index clusters and hash clusters is in the waydata is accessed given a particular cluster key value.

How to do it...

The following steps will demonstrate the use of hash clusters:

  1. Connect to the HR schema of the TESTDB database:

    CONNECT hr@TESTDB/hr
    
  2. Create the cluster:

    CREATE CLUSTER EMP_DEPT_CLUSTER (deptid NUMBER(4))
    SIZE 8192 HASHKEYS 100;
    
  3. Create the first table and populate it with data:

    CREATE TABLE CL_DEPARTMENTS CLUSTER EMP_DEPT_CLUSTER
    (department_id) AS SELECT * FROM DEPARTMENTS;
    
  4. Create the second table, populate it with data, and gather statistics:

    CREATE TABLE CL_EMPLOYEES CLUSTER EMP_DEPT_CLUSTER
    (department_id) AS SELECT * FROM EMPLOYEES;
    EXEC DBMS_STATS.GATHER_TABLE_STATS(‹HR›, ‹CL_EMPLOYEES...