1. 2 Copyright © 2006, Oracle. All rights reserved. Performance Tuning: Overview

2. 2-2 Copyright © 2006, Oracle. All rights reserved. Objectives After completing this lesson, you should be able to do the following: Write appropriate tuning goals Apply the tuning methodology Balance performance and safety trade-offs Identify common tuning problems Log a performance Service Request with Oracle Support

3. 2-3 Copyright © 2006, Oracle. All rights reserved. General Tuning Session Tuning sessions have the same procedure: 1.Define the problem and state the goal. 2.Collect current statistics. 3.Consider some common performance errors. 4.Build a trial solution. 5.Implement and measure the change. 6.Decide: “Did the solution meet the goal?” –No? Then go to step 3 and repeat. –Yes? Then create a new baseline.

4. 2-4 Copyright © 2006, Oracle. All rights reserved.

5. 2-5 Copyright © 2006, Oracle. All rights reserved. Defining the Problem To discover and define the problem: Listen to user feedback Check the alert log and trace files for errors Check the parameter file for any diagnostic or inappropriate parameter setting Check memory, I/O, and CPU usage. Identify processes with resource usage anomalies Identify and tune SQL statements that are heavy consumers of CPU or I/O Collect instance and operating system (OS) statistics

6. 2-6 Copyright © 2006, Oracle. All rights reserved. Setting the Priority Choose the problem that has the greatest impact: Analyze system performance in terms of work done (CPU or service time) versus time spent waiting for work (wait time).DB 타임 감소가 목표 Determine which component consumes the greatest amount of time. Drill down to tune that component, if appropriate.

7. 2-7 Copyright © 2006, Oracle. All rights reserved. Tuning Methodology: Setting the Priority Example Time Model System Stats DB/Inst: ORCL Snaps: 1-11 -> Ordered by % of DB time desc, Statistic name Statistic Time (s) % of DB time --------------------------- --------- --------- sql execute elapsed time 467.0 77.1 DB CPU 414.2 68.4 parse time elapsed 200.5 33.1 hard parse elapsed time 109.0 18.0 … DB time 605.8

8. 2-8 Copyright © 2006, Oracle. All rights reserved. Common Tuning Problems The most common tuning problems: SQL statements Session management Shared pool sizing and contention Buffer cache sizing and contention Data block contention Redo log and redo buffer tuning Undo tuning I/O issues Locking issues

9. 2-9 Copyright © 2006, Oracle. All rights reserved. ADDM Tuning Session ADDM tuning session has the same procedure as the general tuning session, but combines steps: 1.View the ADDM report. A.Collect current statistics; compare with previous set. B.Compare to performance issues knowledge base. C.Define the problem and make recommendations. 2.Review recommendations. D.Build a trial solution. 3.Implement the recommendation. E.Implement and measure the change. 4.Review the next ADDM report. F.Decide: “Did the solution meet the goal?”

10. 2-10 Copyright © 2006, Oracle. All rights reserved. Effective Tuning Goals Effective tuning goals are: Specific Measurable Achievable

11. 2-11 Copyright © 2006, Oracle. All rights reserved.

12. 2-12 Copyright © 2006, Oracle. All rights reserved. Tuning Objectives The objectives of tuning are: Minimizing response time Increasing throughput Increasing load capabilities Decreasing recovery time

13. 2-13 Copyright © 2006, Oracle. All rights reserved. DB Time DB Time = DB Wait Time + DB CPU Time

14. 2-14 Copyright © 2006, Oracle. All rights reserved. CPU and Wait Time Tuning Dimensions Scalable application Possibly needs SQL tuning Needs instance/RAC tuning CPU time Wait time No gain achieved by adding CPUs/nodes DB time = DB CPU time + DB wait time

15. 2-15 Copyright © 2006, Oracle. All rights reserved. Tuning Life Cycle Phases Application life cycle can be divided into different phases: Application design and development Testing: Database configuration Deployment: Adding a new application to an existing database Production: Troubleshooting and tuning

16. 2-16 Copyright © 2006, Oracle. All rights reserved. Tuning Steps During Life Cycle 1.Tune the design. 2.Tune the application. 3.Tune memory. 4.Tune I/O. 5.Tune contention. 6.Tune the operating system.

17. 2-17 Copyright © 2006, Oracle. All rights reserved. Application Design and Development The application can be tuned even in the design and development phases by building and tuning test cases. Check normalization against major functions. Check data structures against access times. Look at points where processes are serialized. Tune the major reports. Tune the high-volume processes.

18. 2-18 Copyright © 2006, Oracle. All rights reserved. Testing: Database Configuration The testing phase allows tuning at a deeper level: Check physical layout. Monitor for resource contention. –Memory utilization –Locks –Disk hot spots Test for resource exhaustion.

19. 2-19 Copyright © 2006, Oracle. All rights reserved. Deployment Deployment of: New application and database –Take baseline. –Monitor growth and performance. New application in existing database –Take baseline before deployment. –Take baseline after deployment. –Compare baselines.

20. 2-20 Copyright © 2006, Oracle. All rights reserved. Production Tuning is reactive. You need to know: What has changed? Where is the baseline?

21. 2-21 Copyright © 2006, Oracle. All rights reserved. Collecting a Baseline Set of Statistics A baseline set of statistics is used to: Provide a set of statistics that are collected when the system is operating within the bounds set Compare the baseline statistics with current statistics Create a hypothesis about what has changed on the system

22. 2-22 Copyright © 2006, Oracle. All rights reserved. Performance Versus Safety Trade-Offs ( 반비례 ) Factors that affect performance: Multiple control files Multiple redo log members in a group Frequent checkpointing Backing up data files Performing archiving Block check sums Number of concurrent users and transactions

23. 2-23 Copyright © 2006, Oracle. All rights reserved. Filing a Performance Service Request File a Performance Service Request: Is the problem instancewide or query specific? Identify the root cause. Provide Statspack or AWR reports, and OS statistics. Provide Remote Diagnostics Agent (RDA) reports. Provide SQL_TRACE reports.

24. 2-24 Copyright © 2006, Oracle. All rights reserved. RDA Report

25. 2-25 Copyright © 2006, Oracle. All rights reserved. Monitoring and Tuning Tool: Overview Alert log Trace files Performance views Optimizer statistics SQL statistics Base statistics Histograms Metrics Service statistics ASH tkprof trcsess System statistics Session statistics Wait model Time model Alerts ASH reports Services

26. 2-26 Copyright © 2006, Oracle. All rights reserved. Monitoring and Tuning Tool: Overview Statspack AWR EM performance pages Metric baseline EM policies ADDM Advisors Direct SGA monitor Hang analyzer Baselines AWR baselines Compare periods Services

27. 2-27 Copyright © 2006, Oracle. All rights reserved. Practice Overview: Write Tuning Goals This practice covers the following topics: Transform a problem definition into a goal Make a goal measurable

28. 2-28 Copyright © 2006, Oracle. All rights reserved. Summary In this lesson, you should have learned how to: Write appropriate tuning goals Identify the proper methodology for tuning in different development phases Balance performance and safety trade-offs Identify common tuning problems Log a performance Service Request with Oracle Support