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 count, min/max, and group-by


In this recipe, we will see how to count rows, compute min/max aggregates, and use filters in group-by queries.

How to do it...

The following steps will demonstrate the use of count, min/max, and group-by:

  1. Connect to the SH schema:

    CONNECT sh@TESTDB/sh
    
  2. Show the execution plan for a MIN/MAX query:

    SET AUTOT TRACE EXP
    SELECT MAX(CUST_CREDIT_LIMIT) FROM CUSTOMERS;
    SELECT MIN(CUST_CREDIT_LIMIT) FROM CUSTOMERS;
    
  3. Show the execution plan for a query which returns the MIN and the MAX:

    SELECT MAX(CUST_CREDIT_LIMIT), MIN(CUST_CREDIT_LIMIT)
    FROM CUSTOMERS;
    
  4. Create an index on CUSTOMERS in the column in which we need to aggregate:

    CREATE INDEX IX_CUST_CREDIT_LIMIT
      ON CUSTOMERS (CUST_CREDIT_LIMIT);
    
  5. Execute the query in step 2:

    SET AUTOT TRACE EXP STAT
    SELECT MAX(CUST_CREDIT_LIMIT) FROM CUSTOMERS;
    SELECT MIN(CUST_CREDIT_LIMIT) FROM CUSTOMERS;
    
  6. Execute the query in step 3:

    SELECT MAX(CUST_CREDIT_LIMIT), MIN(CUST_CREDIT_LIMIT)
    FROM CUSTOMERS;
    
  7. Use different ways to count the...