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Chris Saxon

Thanks for the question, oracle.

Asked: February 03, 2016 - 5:55 am UTC

Last updated: February 04, 2016 - 4:01 am UTC

Version: 11.2.0.3

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Hi tom,

I am working as an oracle database administrator with SQL database also. Till now i am working as an administrator now i have moved to performance tunning team for that i need your help and support that how to read and analyse the AWR Report pls help us.

Currently i am generating AWR Report and check the top 10 queries and generate the execution plan for that queries and check full table scan and ask to the application team to tune this queries then they create an index and tune queries accordingly. After that tunning again i check the execution plan to verify that the full table scan is not now. For that i need your help to recommand application team to create an index on these particular column.


1. Pls help to analyse the AWR Report with partical example. because i have read many blogs and articals but not understand proper.
2. How to read exection plan and recommand the application team to create an index on these columns,do not use much more parallism any many more.
3. What is the filter and access in execution plan.


Pls help
I am very much interest in Performance tunning.

Thanks

and Connor said...

For ASH/AWR, these are some excellent references, done by the people that actually own and build all this stuff.

http://www.oracle.com/technetwork/database/manageability/ppt-active-session-history-129612.pdf

http://www.oracle.com/technetwork/database/manageability/db-perf-tuning-ow08-131582.pdf

http://www.oracle.com/technetwork/cn/database/diag-techniques-presentation-ow07-128491.pdf

For explain plan, Jonathan Lewis has a nice series on it:

http://allthingsoracle.com/tag/execution-plans/

which covers just about anything and everything you could want to know.



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Comments

oracle, February 03, 2016 - 7:01 am UTC

Thanks for your quick reply,

I have gone through the awr related docs but it is more high which i am expecting because i want awr report with each section description to check how read and when the section is high/low then what we will be the case of and what is the solution .

Thanks
Connor McDonald
February 04, 2016 - 4:01 am UTC

Each of those presentations starts high level and gives the appropriate *definitions" that control what you should be looking for in AWR reports (and/or OEM).

It's not about "check how to read and when the section is high/low"... its about what *defines* the performance of my system with respect to the things that define my business responsibilities (eg user response times, nightly load throughput etc).

Understand the terms and concepts in those whitepapers and the sections will take care of themselves.

How to read explain plan

Rajeshwaran, Jeyabal, February 03, 2016 - 8:12 am UTC

wrong approach

Jeff, February 03, 2016 - 7:50 pm UTC

"Currently i am generating AWR Report and check the top 10 queries and generate the execution plan for that queries and check full table scan and ask to the application team to tune this queries then they create an index and tune queries accordingly. After that tunning again i check the execution plan to verify that the full table scan is not now. "

No.

Tablescans are not necessarily bad.

Index lookups are not necessarily good.

There is so much more to tuning SQL than "get rid of the tablescans".

Chris Saxon
February 04, 2016 - 2:35 am UTC

yup

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