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Ash and awr performance data2

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Kellyn Pot'Vin-Gorman
Kellyn Pot'Vin-Gorman

PDF of ASH and AWR Performance data Presentation, Aug. 30th from Redgate Webinar. Webinar is available at Redgate's site.

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Ash and AWR Performance Data Kellyn Pot’Vin Sr. Technical Consultant Enkitec
A Little About Me:  Sr. Technical Consultant for Enkitec  Multi-Platform Tuning Specialist  (Lately) EM12c Specialist  Oracle ACE  Training Days Director for RMOUG  Blog at DBAKevlar.com
Brief History  ASH= Active Session History  AWR= Automatic Workload Repository  Introduced in Oracle 10g  Evolution to statspack, requests for performance reporting improvements.  “Always on” approach to performance metrics with requirement of non-locking collection process.  Requires Management Tuning Pack License from Oracle.
Ash and awr performance data2
Ash and awr performance data2
AWR Repository  Used not only by the AWR reports  Automatic Database Diagnostic Monitor, (ADDM Reporting)  SQL Tuning Advisor  Segment Advisor  By default, snapshots every hour. Retention is for 7 days. Both are modifiable.  Snapshots can be taken at any time: EXEC DBMS_WORKLOAD_REPOSITORY.create_snapshot;
ASH Data  Samples each active database session every second.  Data is held in buffer in memory.  Built into the Oracle kernel and accessed through the v$active_session_history view.  In an AWR snapshot, 1 row in 10 from ASH buffer is placed into the AWR repository.  Managed by the MMNL, (Memory Monitor Lite)  Should not be used to track occurrence.
Running AWR from Enterprise Manager
Running ASH Report from EM • ASH is always by time, not snapshot. • Set start date and time. • End date and time • Generate report
HTML Format ASH
Running Reports, Command Line $ORACLE_HOME/rdbms/admin/awrrpt.sql; $ORACLE_HOME/rdbms/admin/ashrpt.sql; $ORACLE_HOME/rdbms/admin/awrsqlrpt.sql; Less Known AWR Reports: awrinfo.sql General AWR Info awrddrpt.sql Comparison report between snapshots awrblmig.sql Migrates pre-11g baseline data into 11g Baseline tables. awrgrpt.sql RAC Aware AWR Report.
AWR Info Report  Snapshot Interval Information  Basic Info on Instances and Nodes  No User or Application Schema info.  Space Usage by SYSAUX  WRH$ and Non- AWR Objects, ordered by size  Snapshot info and if any errors.  Advisor Tasks
AWR Info Report
ASH Info Report, (cont.)
AWR and ASH in Real Life Scenario  RAC, 2-nodes, Ver. 10.2.0.5  Application Waits Seen in EM Performance Page.  Out of the ordinary CPU Resource usage  50 minutes of time for evaluation. AWR set to 10 min. interval on snapshots.
Run AWR for Timeline Shown in Enterprise Manager Who needs a top five when the top 2 are so impacting?
Top SQL by Elapsed Time
AWR Segment Info
Next Steps Using ASH  Limitingfrom a 50 minute/1 hour view to more definitive view of the database a given timeline.  Top SQL  Top Sessions  Top Waits  Blocking Sessions  Top Objects  Waits by time during sample intervals.
Top Modules and Clients
Top SQL Statements
Blocking Sessions The Blocking Session, along with Top Object should be noted.
Next Step  Kill Blocking Session?  Investigate Further?  InvestigateSQL_ID’s with AWR SQL Two SQL_ID’s are in question: 4z1vnc0995bm6 b6vaxgxt4wh8v
4z1vnc0995bm6- Update
Update Cont.
B6vaxgxt4wh8v- Select
Select Cont.
Long Story Short….  Subsequent ASH reports showed blocked sessions became blocking sessions.  Update statement and select belong to same code. Update is executed, then large select, no commit until AFTER select is complete.  Request to development to commit before select and tuning recommendation from AWR SQL_ID specific report for select statement.
Querying ASH Data Directly  More defined reporting  No need to pull full report  Detail on waits that are of interest  Join to non-AWR objects  Simple queries presented…
V$ACTIVE_SESSION_HISTORY • More Column Data in 11g than shown. • Flags column is for future development. • Broken down into usable sections, easier to query.
Knowing What’s in the ASH Buffer • Deters from making assumptions on what data is being queried. • Know your samples!
Wait Events Across Nodes
Query top 10 SQL_ID’s in the last 10 minutes?
SQL_ID and CPU Usage
IO Waits by Object from ASH
SQL Text with ASH • SQL for most recent five minutes of sample data from ASH
SQL Results • SQL_ID, SQL Text, Sample Time that Process was captured in.
Tyler Muth ASH Mining Query
ASH Mining Output Additional Options: • Physical Read Averages • Physical Writes, (Max/Averages) • Redo Info • Logon Info • Hard Parsing, etc.
Best Practice When Querying ASH Data  Keep it Simple and don’t reinvent the wheel.  Samples are an alias for time, not for counts.  Understand what is valuable and compare to packaged reports.  Be aware on RAC of node specific data.  Take care when querying Obj#, File# and Block#, (still issues in different versions…)  Check the time that is available in buffer, don’t assume!
AWR/ASH Links/Blogs  Karl Arao: http://karlarao.wordpress.com  Tyler Muth: http://tylermuth.wordpress.com/  Kyle Hailey, John Beresniewicz, Graham Wood: http://ashmasters.com/  Mine- “For the Love of ASH and AWR” http://dbakevlar.com/2011/02/for-the- love-of-awr-and-ash/
QUESTIONS Email: dbakevlar@gmail.com Company: http://enkitec.com Website: http://dbakevlar.com User Group: http://www.rmoug.org

More Related Content

Ash and awr performance data2

  • 1. Ash and AWR Performance Data Kellyn Pot’Vin Sr. Technical Consultant Enkitec
  • 2. A Little About Me:  Sr. Technical Consultant for Enkitec  Multi-Platform Tuning Specialist  (Lately) EM12c Specialist  Oracle ACE  Training Days Director for RMOUG  Blog at DBAKevlar.com
  • 3. Brief History  ASH= Active Session History  AWR= Automatic Workload Repository  Introduced in Oracle 10g  Evolution to statspack, requests for performance reporting improvements.  “Always on” approach to performance metrics with requirement of non-locking collection process.  Requires Management Tuning Pack License from Oracle.
  • 6. AWR Repository  Used not only by the AWR reports  Automatic Database Diagnostic Monitor, (ADDM Reporting)  SQL Tuning Advisor  Segment Advisor  By default, snapshots every hour. Retention is for 7 days. Both are modifiable.  Snapshots can be taken at any time: EXEC DBMS_WORKLOAD_REPOSITORY.create_snapshot;
  • 7. ASH Data  Samples each active database session every second.  Data is held in buffer in memory.  Built into the Oracle kernel and accessed through the v$active_session_history view.  In an AWR snapshot, 1 row in 10 from ASH buffer is placed into the AWR repository.  Managed by the MMNL, (Memory Monitor Lite)  Should not be used to track occurrence.
  • 8. Running AWR from Enterprise Manager
  • 9. Running ASH Report from EM • ASH is always by time, not snapshot. • Set start date and time. • End date and time • Generate report
  • 11. Running Reports, Command Line $ORACLE_HOME/rdbms/admin/awrrpt.sql; $ORACLE_HOME/rdbms/admin/ashrpt.sql; $ORACLE_HOME/rdbms/admin/awrsqlrpt.sql; Less Known AWR Reports: awrinfo.sql General AWR Info awrddrpt.sql Comparison report between snapshots awrblmig.sql Migrates pre-11g baseline data into 11g Baseline tables. awrgrpt.sql RAC Aware AWR Report.
  • 12. AWR Info Report  Snapshot Interval Information  Basic Info on Instances and Nodes  No User or Application Schema info.  Space Usage by SYSAUX  WRH$ and Non- AWR Objects, ordered by size  Snapshot info and if any errors.  Advisor Tasks
  • 14. ASH Info Report, (cont.)
  • 15. AWR and ASH in Real Life Scenario  RAC, 2-nodes, Ver. 10.2.0.5  Application Waits Seen in EM Performance Page.  Out of the ordinary CPU Resource usage  50 minutes of time for evaluation. AWR set to 10 min. interval on snapshots.
  • 16. Run AWR for Timeline Shown in Enterprise Manager Who needs a top five when the top 2 are so impacting?
  • 17. Top SQL by Elapsed Time
  • 19. Next Steps Using ASH  Limitingfrom a 50 minute/1 hour view to more definitive view of the database a given timeline.  Top SQL  Top Sessions  Top Waits  Blocking Sessions  Top Objects  Waits by time during sample intervals.
  • 20. Top Modules and Clients
  • 22. Blocking Sessions The Blocking Session, along with Top Object should be noted.
  • 23. Next Step  Kill Blocking Session?  Investigate Further?  InvestigateSQL_ID’s with AWR SQL Two SQL_ID’s are in question: 4z1vnc0995bm6 b6vaxgxt4wh8v
  • 28. Long Story Short….  Subsequent ASH reports showed blocked sessions became blocking sessions.  Update statement and select belong to same code. Update is executed, then large select, no commit until AFTER select is complete.  Request to development to commit before select and tuning recommendation from AWR SQL_ID specific report for select statement.
  • 29. Querying ASH Data Directly  More defined reporting  No need to pull full report  Detail on waits that are of interest  Join to non-AWR objects  Simple queries presented…
  • 30. V$ACTIVE_SESSION_HISTORY • More Column Data in 11g than shown. • Flags column is for future development. • Broken down into usable sections, easier to query.
  • 31. Knowing What’s in the ASH Buffer • Deters from making assumptions on what data is being queried. • Know your samples!
  • 33. Query top 10 SQL_ID’s in the last 10 minutes?
  • 34. SQL_ID and CPU Usage
  • 35. IO Waits by Object from ASH
  • 36. SQL Text with ASH • SQL for most recent five minutes of sample data from ASH
  • 37. SQL Results • SQL_ID, SQL Text, Sample Time that Process was captured in.
  • 38. Tyler Muth ASH Mining Query
  • 39. ASH Mining Output Additional Options: • Physical Read Averages • Physical Writes, (Max/Averages) • Redo Info • Logon Info • Hard Parsing, etc.
  • 40. Best Practice When Querying ASH Data  Keep it Simple and don’t reinvent the wheel.  Samples are an alias for time, not for counts.  Understand what is valuable and compare to packaged reports.  Be aware on RAC of node specific data.  Take care when querying Obj#, File# and Block#, (still issues in different versions…)  Check the time that is available in buffer, don’t assume!
  • 41. AWR/ASH Links/Blogs  Karl Arao: http://karlarao.wordpress.com  Tyler Muth: http://tylermuth.wordpress.com/  Kyle Hailey, John Beresniewicz, Graham Wood: http://ashmasters.com/  Mine- “For the Love of ASH and AWR” http://dbakevlar.com/2011/02/for-the- love-of-awr-and-ash/
  • 42. QUESTIONS Email: dbakevlar@gmail.com Company: http://enkitec.com Website: http://dbakevlar.com User Group: http://www.rmoug.org