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Oracle Performance Tuning and Optimization
(Publisher: Macmillan Computer Publishing)
Author(s): Edward Whalen
ISBN: 067230886x
Publication Date: 04/01/96

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What To Test in the RDBMS

You should test the RDBMS keeping functionality, load testing, and performance in mind. Make sure that the system will function as specified. Try to use a test database that is configured and sized similar to the production database.

Once you build an effective load test with repeatable results, start changing some of the parameters described in Part II of this book and earlier in this chapter. By changing only one parameter at a time, you can easily see which changes affect performance.

Before changing anything, set your expectations for the changes you are going to make. If the results don’t turn out as expected, try to understand why they didn’t. Be sure to log the results so that you have a reference of what changes were effective and what changes were not.

What To Test in the OS

For the most part, the OS is tested with the RDBMS. If you have to change some specific OS parameter to increase a limitation, you usually don’t have to retest the performance. Any limit change is usually associated with an RDBMS change, and the two can be tested together.

Other OS changes such as feature enhancements should be tested with the RDBMS, but you should more closely watch and analyze these results. You should carefully analyze things such as scheduler changes and cache affinity that may have an adverse affect on the system to verify that performance has not degraded.

As stated earlier in this book, the OS is primarily a vehicle for the RDBMS to use. The primary goal in tuning the server OS is to reduce overhead and optimize the I/O, memory, and networking subsystems.

Benchmarks

Standardized benchmarks are a good way to judge how well a system is performing and to use as a comparison between different hardware platforms. If they are available to you, standardized benchmarks are also a good way to analyze the performance of your particular platform.

Using a standardized benchmark (such as the TPC-D benchmark) is not a good way to tune your system. You should tune each system individually, based on its own characteristics. Examine the Full Disclosure Report (FDR) submitted by the test sponsor to see a breakdown of performance by query type. Look at the performance for the particular query types you use in your operation. Doing so may give you some indication of how well the testing configuration would work in your environment.

A system tuned for a benchmark such as the TPC-D benchmark may provide useful tuning hints. Because the primary goal of a TPC benchmark is for the sponsor to get the best possible performance, you can see how the sponsors have optimally tuned their systems.

Because an official TPC-D benchmark using Oracle is usually submitted by the hardware manufacturers, OS vendors, and Oracle, you can be assured that the system has been tuned as optimally as possible. If you can, obtain a Full Disclosure Report from the TPC (on the Web at this URL:http://www.tpc.org); look at the way the system was designed and tuned.

Of course, the best benchmark to use on your DSS system is one of your own production decision-support queries. This benchmark provides you with all the information you need to judge the amount and size of the hardware required. Such a customized benchmark also can provide you with valuable information about any configuration changes you make.

Summary

The decision support field has been growing in the last few years. With the introduction of faster and less-expensive computer systems, more and more businesses can take advantage of decision support systems. In fact, decision support is now becoming very mainstream.

This chapter looked at the characteristics of this system from the perspectives of a business model and data access. In the next few years, DSS machines will be in use in areas that have not even been thought of yet. As the cost of computing continues to fall and the speed of computing increases, innovative ways of using DSS systems will emerge.


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