RE: No Nulls? (was: Warehouse design: snowflake vs star schem

Mon, 14 Oct 2002 14:36:39 -0700

Title: Message
That's not a problem for me...I told all my duh-velopers that RBO was dropped from Oracle8i............(big grin)
-----Original Message-----
From: Ora NT DBA [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 14, 2002 5:53 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: No Nulls? (was: Warehouse design: snowflake vs star schem

Both would likely do FTS since at any given time more than
50% of your employees will be current (have an end date
of 1/1/4000' making it very unlikely that the cbo would choose
this index.  The RBO, would, but it would likely degrade
not improve your performance.  

John

Grabowy, Chris wrote:
Hmmm...but what about the index?  Which is faster?
 
select * from table where END_EMPLOYMENT IS NULL;
 
OR
 
select * from table where END_EMPLOYMENT = '01/01/4000';
 
I like NULL, but I am leaning towards Igor, and others, to agree upon and use a default value, or a "business sense" replacement value for NULL.  I want to be able to take the awesome advantage of an index...versus FTS? 
 
Am I headed in the wrong direction??  Any other thoughts??
-----Original Message-----
From: Fink, Dan [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 14, 2002 4:49 PM
To: Multiple recipients of list ORACLE-L
Subject: RE: No Nulls? (was: Warehouse design: snowflake vs star schem

The problem I see with NO NULLS is that artificial data must be created, where the data is truly not known. Whether you deal with NULLs or artificial data, you will always have to code accordingly, so it is a wash. Igor's example is an good one. When I write an app to access the END_EMPLOYMENT date, I must handle a date of '01/01/4000'. Or I can handle the NULL condition. As a person who has had to support some very convoluted code, I'd rather deal with NULL. What if the employee record contained TERM_CODE? I would rather have the value NULL, meaning they have not been terminated rather than dealing with hard-coded or lookup values.
-----Original Message-----
From: Igor Neyman [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 14, 2002 2:14 PM
To: Multiple recipients of list ORACLE-L
Subject: Re: No Nulls? (was: Warehouse design: snowflake vs star schem

END_EMPLOYEMENT date for still employed employees equals to "01/01/4000" (or any other pre-defined date in distant future).
 
Igor Neyman, OCP DBA
[EMAIL PROTECTED]
 
 
 
----- Original Message -----
Sent: Monday, October 14, 2002 3:39 PM
Subject: RE: No Nulls? (was: Warehouse design: snowflake vs star schem

"No application that I can reasonably think of should
use NULLS, except those pre-81
where there are obsolete columns."

Everytime somebody says this to me, I ask them:

How do you handle still employed employees in an EMPLOYEE table
that contains a END_EMPLOYEMENT date column?

What's your take?
----
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-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Monday, October 14, 2002 2:29 PM
To: Multiple recipients of list ORACLE-L
Subject: Re:No Nulls? (was: Warehouse design: snowflake vs star schem


Jesse,

    I'll refrain from personal comments, but on CJ's quote, he's correct.  Nulls
are an oddity.  They cannot be true or false (<column_name> = NULL or
<column_name> != NULL), nor can they equal anything.  They are in effect a third
logical state of nothingness.  You also have to code most applications with
indicator variables to check for their existence.  All in all a real pain in the
backside.  BUT, if you give me the possibility that nulls exist in the data I
much prefer using them vs. many a third party solution of a single space.  No
application that I can reasonably think of should use NULLS, except those pre-81
where there are obsolete columns.

Dick Goulet

____________________Reply Separator____________________
Author: "Jesse; Rich" <[EMAIL PROTECTED]>
Date:       10/14/2002 9:33 AM

On the link below is this quote from C.J.Date:

"I don't want you to think that my SQL solution to your problem means I
advocate the use of nulls.  Nulls are a disaster."

Of course, he doesn't expound upon it (probably not a need except for
dummies like me).  Anyone care to comment?  (On the quote, not on my
dumminess...)


Rich


Rich Jesse                           System/Database Administrator
[EMAIL PROTECTED]              Quad/Tech International, Sussex, WI USA

> -----Original Message-----
> From: Robson, Peter [mailto:[EMAIL PROTECTED]]
> Sent: Monday, October 14, 2002 4:59 AM
> To: Multiple recipients of list ORACLE-L
> Subject: RE: Warehouse design: snowflake vs star schemas
>
>
> Just for the record (and perhaps to confirm that there are
> always two sides
> to a story). Readers may like to see the article Chris Date
> wrote to Ralph
> Kemball on the subject of business rules and integrity constraints:
>
> http://www.dbdebunk.com/kimball1.htm
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