RE: Generate RANDOM number

You asked what is wrong with his select.

Probably he is seeking information regarding the quality of the pseudo random sequence that is generated.

You see, short of the "I bet you can't get your hands on one" quantum mechanics based logic chips it is simply impossible for digital computers to generate numbers that are actually random. Various algorithms exist starting with various seeds, and there are formal metrics regarding the quality of the random sequence including such notions as a relatively flat histogram of values in the produced range without supporting the Monte-Carlo fallicy in fact.

Consider producing a target range of 1 to 1,000. You'd hope that after 1,000,000 generated numbers the histogram totals would be near 1,000 for each value. And yet if your algorithm was certain to produce exactly 1,000 of each number then you'd have a real problem calling the millionth number generated "random" since you could know that it must fill in the last remaining value that only had 999 so far.

On the other hand if you want a very flat psuedo random seed based set of number to drive engineering test perturbation values as opposed to security sequences or anything sensitive to predictability, a generator that generators exactly 1000 in each bucket might be just fine.

Okay, now that I've made all the numeric methods scientists in the lurkership puke at my gross oversimplification, my guess is still:

Probably he is seeking information regarding the quality of the pseudo random sequence that is generated.

And whether someone has published a superior routine (or one merely different but more suited to his purposes, of which I am uncertain.)

I regret to say I am at a loss to direct you to the documentation (if it exists) on the value distribution, skewness, kurtosis, etc., etc. of the dbms_random.value() function.

So while I can't answer his question definitely, I hope I've answered your question. Maybe he'll comment on my guess.

Regards,

mwf

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org]On Behalf Of Igor Neyman Sent: Tuesday, January 04, 2005 3:13 PM
To: Muqthar.Ahmed_at_decoratetoday.com; oracle-l_at_freelists.org Subject: RE: Generate RANDOM number

Why do you need other recommendations?
What's wrong with your "select"?

Igor Neyman, OCP DBA
ineyman_at_perceptron.com

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Muqthar Ahmed Sent: Tuesday, January 04, 2005 2:39 PM
To: 'oracle-l_at_freelists.org'
Subject: RE: Generate RANDOM number

Hi,

The one I am using is:

SELECT dbms_random.value(1000000000000001,9999999999999999) FROM   dual;

any other recommendations???

Thanks
Muqthar

-----Original Message-----

From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Muqthar Ahmed Sent: Tuesday, January 04, 2005 2:08 PM
To: 'oracle-l_at_freelists.org'
Subject: Generate RANDOM number

Hi,

I have to generate 16 digit random numbers.......any recommendations. I am using Oracle 9.2.x release.

Thanks
Muqthar Ahmed
Oracle9i Certified DBA

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http://www.freelists.org/webpage/oracle-l Received on Tue Jan 04 2005 - 16:12:34 CST