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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Caught YAPPing
Thank You for your response Cary. You say "The important thing is that you have to segment your transactions into different lists". I did convey something similar to the requestor. I have now put the ball back in their court, by telling them to identify some crucial functions or precise statements that they would need to monitor as such. I dont expect to hear back from them.
Anyways, this is a request from the management, and they like to see things in graphs with spikes, and ratios. I got a crude way to do this for now. I am presently capturing some baseline, acceptable wait times for some of the key wait events. I then plan to utilize statspack to take snapshots every hour, and code for scripts to query the underlying tables. If anything exceeds the accepted values, shoot out alerts. Then, I plan to use the statsviewer tool (http://www.geocities.com/alexdabr/spstd.html)
Thank you for your insight. I look forward to the book.
Raj
"Cary Millsap"
<cary.millsap_at_h To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
otsos.com> cc:
Sent by: Subject: RE: Caught YAPPing
root_at_fatcity.co
m
January 17,
2003 01:50 PM
Please respond
to ORACLE-L
Raj,
You can of course compute the average any list of numbers. However, if your list contains data from fundamentally different types of data, then your average will be meaningless. Example:
A = {Response times for program 'a'} = {20:58.13, 42:19.28, 34:11.23} B = {Response times for program 'b'} = {00:00.79, 00:00.42, 00:00.65}
Then we have:
Mean(A) = 1,949.547 seconds Mean(B) = 0.620 seconds Mean(A union B) = 975.083 seconds
So the real question is "does Mean(A union B) really mean anything?" The answer is no, because A and B come from radically different distributions. If you want to see some real problems here, imagine what happens when B has 15,000 elements in it per day and A has 20 per day. What does the combined average tell you? Nothing much, really, except for contrivances like...
This type of phenomenon is an important part of the reason why any method that uses count-based ratios (i.e., "hit ratios") to tune a database is an unreliable method.
On the other hand, if you're recording response times for only a single particular type of transaction (e.g., one list only for A, and another list only for B), then the averages (Mean(A) and Mean(B)) should be extremely instructive. The important thing is that you have to segment your transactions into different lists.
For response times, the criterion for splitting a list like "A union B" into separate lists like "A" and "B" is that the data in each individual list should fit the so-called "exponential distribution". To figure out whether a given list fits that distribution, you can either dust off your old statistics books, or you can wait until about June and use the Perl code that'll be supplied in the "Optimizing Response Time" book (O'Reilly) I'm working on.
Cary Millsap
Hotsos Enterprises, Ltd.
http://www.hotsos.com
Upcoming events:
- 2003 Hotsos Symposium, Feb 9-12 Dallas
-----Original Message-----
Rajesh.Rao_at_jpmchase.com
Sent: Thursday, January 16, 2003 12:24 PM
To: Multiple recipients of list ORACLE-L
Hello Everyone,
Is there anything, called an "Average Response Time" for an Oracle database? I got a request from one of the application owners as under :
< Snip>
If I can get a log of AVERAGE response time for 1/2 hour periods
starting
at 9am and running thru 5 pm I would be in heaven. If I cannot get
this,
what would be of similar help. Here is an example of what I would like
to
see, say, for today:
Time Average Response time 9-9:30 2.3 sec 9:30-10 3.0 sec 10-10:30 3.3 sec 10:30-11 3.3 sec 11-11:30 4.5 sec
When we get to 10 seconds we have trouble. If we have spikes we can try
to
figure out why. ALso, the cost of the above would be a factor. We
have
NO money for this.
<End Snip>
How can I get this from system or session wait tables or v$sysstat? Any ideas?
Regards
Raj
-- Please see the official ORACLE-L FAQ: http://www.orafaq.net -- Author: INET: Rajesh.Rao_at_jpmchase.com Fat City Network Services -- 858-538-5051 http://www.fatcity.com San Diego, California -- Mailing list and web hosting services --------------------------------------------------------------------- To REMOVE yourself from this mailing list, send an E-Mail message to: ListGuru_at_fatcity.com (note EXACT spelling of 'ListGuru') and in the message BODY, include a line containing: UNSUB ORACLE-L (or the name of mailing list you want to be removed from). You may also send the HELP command for other information (like subscribing).Received on Fri Jan 17 2003 - 14:44:00 CST
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