If I run ADDM report every day for about a week,I am getting an ADDM recommendation to increase the Ssize of the current SGA size and 20-30% approximate performance gain was measured by ADDM.

We are using automatic memory management.

But If i run the Memory advisor every time it says that the current SGA size is adequate.From the advisor graph for the recommended value of sga_target size from ADDM,the percentage gain on DB time would be insignificant.

I would like to know why Oracle memory advisor doesn't reflecting the recommendations from ADDM over a period of time.

Thanks

bryan123,

Thank you for such an interesting inquiry. However, this request appears to be difficult to address, considering the scope of the question. Luckily, there is plenty of information within our Burleson article library. Below are some examples of how you can search our library to find the necessary articles that will collectively answer your question.

http://www.google.com/search?hl=en&saf...on+ADDM+report+
Searching Burleson with ADDM Reports, you will find several articles that address various aspects of ADDM:

• Oracle ADDM Analysis
• Oracle ADDM Example
• The Oracle Database Advisors, Part 2 Robert Freeman
• Oracle DBA Forums > ADDM finding - Streams capture: waiting for ...

http://www.google.com/search?hl=en&saf...Memory+advisor+
Site searching Oracle Memory Advisor will also bring in links to informative Burleson articles:

• Oracle 10g Memory Advisor


http://www.google.com/search?hl=en&saf...+size+from+ADDM
Sometimes, searching appropriate terms still takes some digging. Here, the term “burleson wrong sga_target size from ADDM” brings an OTN Forum post, SGA Info ..., in which Don Burleson has posted some great links to a question with similar components. One of those links is http://www.dba-oracle.com/t_amm_automatic_memory_resize.htm which discusses common issues with Automatic Memory Management. There is also a link to http://www.oracle-base.com/articles/10g/Au...cMonitor10g.php which discusses SGA size monitoring over time by ADDM

For more information on search techniques, try making use of this great article: http://www.dba-oracle.com/t_google_keyword_searching.htm

Good Luck!

"it says that the current SGA size is adequate"

Well, a too-small SGA manifests with excessive disk I/O. Is that a problem for you?

It's probably true, but find out. Take a STATSPACK or AWR report and look at the SGA advisors, they will tell you:

http://www.dba-oracle.com/art_builder_buffers.htm

http://www.dba-oracle.com/oracle10g_tuning...ory_advisor.htm



"We are using automatic memory management."

So, the ADDM recommendations are moot.

I don't like ASM, it's unreliable in 10g, but there may be bug fixes:

AMM resizing can hurt performance:

http://www.dba-oracle.com/t_amm_automatic_memory_resize.htm