Oracle® Database 10g Insider Solutions

Performing Baselining

We alluded to a baseline before, and will define and detail it in this section. An AWR baseline is a collection of snapshots usually taken over a representative time period. For example, you might record a baseline where the system is performing well at peak load. You can then use this baseline as a way of comparing statistics captured during a period of bad performance. This baseline comparison can help pinpoint certain statistics that have changed significantly as compared to the period when the database was performing well. You can then analyze the statistics that differ vastly to determine the cause of the problem. Baselines can also be used with SQL tuning sets; we talk about this in detail in a Chapter 13, “Effectively ...