Database Reference
In-Depth Information
Figure 5-7. Defining time range for log analysis
During a performance review, you can analyze the system-level behavior of the database by comparing the
current value of performance counters with the latest baseline. Take the following considerations into account while
comparing the performance data:
Use the same set of performance counters in both cases.
Compare the minimum, maximum, and average values of the counters as applicable for the
individual counters. I explained the specific values for the counters earlier.
Some counters have an absolute good/bad value, as mentioned previously. The current value
of these counters need not be compared with the baseline values. For example, if the current
average value of the Deadlocks/min counter is 10, it indicates that the system is suffering from
a large number of deadlocks. Even though it does not require a comparison with the baseline,
it is still advantageous to review the corresponding baseline value because your deadlock
issues might have existed for a long time. Having the archived baseline logs helps detect the
evolving occurrence of the deadlock.
Some counters do not have a definitive good/bad value. Because their value depends on the
application, a relative comparison with the corresponding baseline counters is a must. For
example, the current value of the User Connections counter for SQL Server does not signify
anything good or bad with the application. But comparing it with the corresponding baseline
value may reveal a big increase in the number of user connections, indicating an increase in
the workload.
 
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