RE: Queueing Theory in Oracle
Date: Tue, 11 Mar 2014 20:36:54 +0000
Message-ID: <CE70217733273F49A8A162EE074F64D901DE25F2_at_exmbx05.thus.corp>
I was thinking more of the way the data might introduce variability in the time required to execute queries - for example in an order placing system a "product pick" query that supplies 20 full names and product IDs for the user to choose from will take longer than a query that supplies only one option. Was there enough variation in the required service time to allow a non-normal distribution ?
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
_at_jloracle
From: Ls Cheng [exriscer_at_gmail.com]
Sent: 11 March 2014 20:23
To: Jonathan Lewis
Cc: Oracle Mailinglist
Subject: Re: Queueing Theory in Oracle
Hi
I thought the reasons of getting normal data distribution was probably how the test is run. Since it's a constant 300/420 users running probably 30 or 40 different SQL statements ( I dont know how many are there in a TPC test), the server was only 18% loaded, the database metric I used were gathered from v$sysmetrc (so I have metric rates in per second unit gathered every minute), all mix together the distribution I got was normal, I even took the sample data and used Cary's mdist.pl<http://mdist.pl> to see if the data was exponentially distributed and all were rejected. After checking that and think a bit then I think the normal data distribution is expected, if I am running 16 TPC transactions per second and there are few in the lower side a few in the higher side and most were in the middle then of course it's a normal data distribution, why should I expect it to be exponentially distributed?
I used TPS as arrival rate and little's law to get the service time (used host cpu as utilization)
system utilization = (arrival rate * service time) / number of servers
The service time was normal distributed as well
So using the TPC test sample data, the formulas I could find (I have downloaded probably 20 PPT from 7 or 8 universities statistics courses) they just dont "glue" together in an Oracle Database and that is why I am asking if anyone has successfully used queueing theory in Oracle so at least I can get some points and see what I am dong wrong :-)
Thanks
On Tue, Mar 11, 2014 at 9:07 PM, Jonathan Lewis <jonathan_at_jlcomp.demon.co.uk<mailto:jonathan_at_jlcomp.demon.co.uk>> wrote:
That's an interesting observation - but (viewed from the outside) I would be a little suspicious that the normal distribution was an artifact of the data generation mechanism and the test mechanism.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
_at_jloracle
From: Ls Cheng [exriscer_at_gmail.com<mailto:exriscer_at_gmail.com>] Sent: 11 March 2014 20:01
To: Karl Arao
Cc: Jonathan Lewis; Oracle Mailinglist
Subject: Re: Queueing Theory in Oracle
I ran last week a couple of TPC load with 300 and 420 users then I used both transaction per second and logical reads per second metric and both showed normal data distribution and that is why I have doubts of how to use queueing theory in Oracle.
From your paper was you able to predict the change from v1 to x2 without run the actual test? Then run the test and validate the prediction?
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