Oracle Performance Tuning – How to Use AWR ?

Here are few silver bullets to use AWR for diagnosing performance issues ….. AWR – Automatic Workload Repository Detailed & comprehensive performance history Based on “snapshot” (time interval) Automatic Database Diagnostic Monitor (ADDM) About 79 DBA_HIST_* “tables” Defaults: Hourly snapshots Weekly retention (month is better) Overview of important AWR tables DBA_HIST_SNAPSHOT PK: SNAP_ID DBID, INSTANCE_NUMBER […]

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Tuning indexes on RAC environments-3

Reversing the index key This is accomplished by executing the following SQL statement: ALTER INDEX <index_name> REBUILD REVERSE; A reverse key index will invert the bytes of the index key column, so that values originally stored in the same block may be spread across multiple index leaf blocks. That will reduce buffer busy contention especially […]

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Tuning indexes on RAC environments-2

Globally busy buffers due to contention for index leaf and branch blocks As we discussed in previous sessions, because of batch INSERT high concurrency could occur for a relatively small set of index leaf and branch blocks, where index keys are populated with monotonically ascending values.The symptoms are increased frequencies and wait times for a […]

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Oracle Support – Useful Metalink References

Patch Set Updates for Oracle Products [ID 854428.1] Quick Guide to Avoid Issues in Creating DB Control Using EMCA [ID 750768.1] Interesting links around Autoconfig in the E-Business-Suite [ID 949160.1] Oracle E-Business Suite Recommended Performance Patches [ID 244040.1] CMCLEAN.SQL – Non Destructive Script to Clean Concurrent Manager Tables [ID 134007.1] Cloning Oracle Applications Release 11i […]

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Understand each sections of AWR

AWR report is broken into multiple parts. 1)Instance information:- This provides information the instance name , number,snapshot ids,total time the report was taken for and the database time during this elapsed time. Elapsed time= end snapshot time – start snapshot time Database time= Work done by database during this much elapsed time( CPU and I/o […]

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AWR and Performance Tuning

Oracle 10g provides a wealth of features, and my favorite among them is AWR. AWR has come to my rescue in critical situations where our  customers face performance issues. AWR collects database performance statistics and metrics for analysis and tuning, shows the exact time spent in the database, and even saves session information Performance can […]

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