You notice a performance change in your production Oracle database and you want to know
which change has made this performance difference.
You generate the Compare Period Automatic Database Diagnostic Monitor (ADDM) report to
further investigation.
Which three findings would you get from the report?
A.
It detects any configuration change that caused a performance difference in both time periods.
B.
It identifies any workload change that caused a performance difference in both time periods.
C.
It detects the top wait events causing performance degradation.
D.
It shows the resource usage for CPU, memory, and I/O in both time periods.
E.
It shows the difference in the size of memory pools in both time periods.
F.
It gives information about statistics collection in both time periods.
Explanation:
Keyword: shows the difference.
* Full ADDM analysis across two AWR snapshot periods
Detects causes, measure effects, then correlates them
Causes: workload changes, configuration changes
Effects: regressed SQL, reach resource limits (CPU, I/O, memory, interconnect)
Makes actionable recommendations along with quantified impact
* Identify what changed
/ Configuration changes, workload changes
*Performance degradation of the database occurs when your database was performing optimally
in the past, such as 6 months ago, but has gradually degraded to a point where it becomes
noticeable to the users. TheAutomatic Workload Repository (AWR) Compare Periods report
enables you to compare database performance between two periods of time.
While an AWR report shows AWR data between two snapshots (or two points in time), the AWR
Compare Periods report shows the difference (ABE) between two periods (or two AWR reports
with a total of four snapshots). Using the AWR Compare Periods report helps you to identify
detailed performance attributes and configuration settings that differ between two time periods.
Reference: Resolving Performance Degradation Over Time
ABD
http://www.moug.org/moug_downloads/moug2012-OEM%2012%20New%20Capabilities%20MOUG.pdf
ABD
A B and D
ABD
ABD
The Compare Period ADDM, as opposed to the former method, performs a cause-to-effect analysis.
1. It first identifies the system changes that may have caused the performance change. For example, it detects a configuration change in DB version, or a workload change with SQL changes. These causes can cause performance difference.
2. Then it identifies the effects of these particular changes. For that purpose, it runs an ADDM analysis for the base period and one for the compare period and then measures the differences between both periods.
3. Finally, it maps the effects to the causes with rule sets. For example, an SGA_TARGET increase can cause an I/O increase. Compare Period ADDM provides more than what you had before with former methods, the identification of changes and an intelligent cause to effect analysis. Is the change due to changes in the workload? Did some new application start running? Were there some changes at the OS level? Was an instance parameter changed?
The report displays changes in the resource demand at the hardware and software levels. These and other questions are more easily answered using this advisor than with the previous AWR Compare Periods reports.
Hence the correct choices are: A, B, D
ABD & E
This report also shows the differences in memory pool sizes if any. See youtube demo
https://www.youtube.com/watch?v=7Ag5uQcMS1Y
ABD
The Automatic Workload Repository (AWR) Compare Periods report enables you to compare database performance between two periods of time. While an AWR report shows AWR data between two snapshots (or two points in time), the AWR Compare Periods report shows the difference (ABE) between two periods (or two AWR reports with a total of four snapshots). Using the AWR Compare Periods report helps you to identify detailed performance attributes and configuration settings that differ between two time periods. Full ADDM analysis across two AWR snapshot periods Detects causes, measure effects, then correlates them Causes: workload changes, configuration changes Effects: regressed SQL, reach resource limits (CPU, I/O, memory, interconnect) Makes actionable recommendations along with quantified impact
1. It identifies the system changes that may have caused the performance change. For example, it detects a configuration change in DB version, or a workload change with SQL changes. These causes can cause performance difference.
2. Then it identifies the effects of these changes. For that purpose, it runs an ADDM analysis for the base period and one for the compare period and then measures the differences.
3. Finally, it maps the effects to the causes with rule sets. For example, an SGA_TARGET increase can cause an I/O increase. Compare Period ADDM provides more than what you had before with former methods, the identification of changes and an intelligent cause to effect analysis. Is the change due to changes in the workload? Did some new application start running? Were there some changes at the OS level? Was an instance parameter changed?
The report displays changes in the resource demand at the hardware and software levels. The report normalizes the statistics by the amount of time spent on the database for each time period and presents statistical data ordered by the largest difference between the periods. For example compare two reports should identify “configuration settings”, “workload profile”, and “statistics” that were different in these two time periods.
A, D, F