A poorly performing system can degrade the performance of all databases and applications deployed on that system. No amount of database, application, or SQL tuning can improve performance when a poorly implemented system is causing performance problems. Applications access databases and both are implemented on an overall system environment, as shown in Figure 10-1. Therefore, a system problem can cause all databases and applications to perform poorly, just like a database problem can cause all applications that access that database to perform poorly.
Figure 10-1. The tuning boxes