Determining Performance Impact for Altering your SGA or PGA
Determining Performance Impact for Altering your SGA or PGA
You can use the Memory Advisor to do what-if analysis for adding or removing physical memory to your database. This advisor graphically analyses the database performance impact of altering your SGA or PGA targets.
To gain advice on configuring the total size of your SGA, on the Memory Parameters: SGA Page, click Advice next to Total SGA Size.
The SGA Advice graph appears. Refer to Figure 10–8, "SGA Size Advice" . Improvement in DB Time (%) is plotted against Total SGA size. A higher number for
Improvement in DB Time is better for performance. In this example, the graph tells us that an SGA size larger than 1000MB will not improve performance by much. Thus 1000MB is the recommended optimal SGA size.
Figure 10–8 SGA Size Advice
Similarly, to run the PGA advisor, navigate to the PGA property page. Next to Aggregate PGA Target, click Advice. The PGA Target Advice Page appears, plotting Cache hit percentage against PGA Target memory size.
10-16 Oracle Database 2 Day DBA
Cache hit percentage is the percentage of read requests serviced by memory, as opposed to those requests serviced by reading from disk, which is slower. A higher hit percentage indicates better cache performance. The optimal zone for cache hit percentage is between 75 and 100 percent. However, it is not safe to conclude that your database is having performance problems simply because your cache hit percentage is not within the optimal zone. When the amount of currently available PGA memory is not adequate for optimal performance, ADDM will automatically recommend adjusting this value with a performance finding.
Monitoring and Tuning: Oracle by Example Series
Oracle by Example (OBE) has a series on the Oracle Database 2 Day DBA book. This OBE steps you through the tasks in this chapter, and includes annotated screen shots.
To view the Monitoring OBE, point your browser to the following location: http://www.oracle.com/technology/obe/10gr2_2day_dba/monitoring/monitoring.htm
Monitoring and Tuning the Database 10-17
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Managing Oracle Software
This chapter describes how to keep your Oracle software up-to-date with patch releases. This chapter contains the following topics:
About Software Management and Patch Releases
Applying a Patch Release
About Software Management and Patch Releases
Software management involves keeping your Oracle software up-to-date with the latest product fixes.
Periodically, Oracle issues product fixes for its software called patch releases. Patch releases are fully tested product fixes only. They do not include new functionality. Application of a patch release affects the software residing in your Oracle home only, with no upgrade or change to the database.
Patches are individual bug fixes. Patch sets are a collection of bug fixes up to the time of the patch set release.
All patch and patch set releases carry version numbers. For example, if you bought Oracle 10g Release 10.2.0.1, then an available patch set might be 10.2.0.2. Every patch or patch set also has a patch number to identify it.
Every patch release has an associated README file that describes its bug fixes. The README also has instructions for manually applying the patch.
Enterprise Manager enables you to find the latest patch release on the Oracle MetaLink Web site and to download it to your Oracle home.
Applying a Patch Release
The steps involved in applying a patch are as follows:
Determining your Oracle Software Environment
Setting Your Oracle MetaLink Credentials
Staging the Patch Release
Installing the Patch Release
Determining your Oracle Software Environment
To select the appropriate patch for your environment, you need to know:
What version of the Oracle database you are running
Managing Oracle Software 11-1
The location of your Oracle home.
What type of hardware configuration you have You can find this information in the General section of the Database Home page, as
shown in Figure 11–1 .
Figure 11–1 General Section of Database Home Page