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Steve Jones is the editor of SQLServerCentral.com and visits a wide variety of data related topics in his daily editorial. Steve has spent years working as a DBA and general purpose Windows administrator, primarily working with SQL Server since it was ported from Sybase in 1990. You can follow Steve on Twitter at twitter.com/way0utwest

NetFlix and Null

There are some progressive companies out there, and I think they are doing some very interesting things with how they treat employees and work with them. One thing that Netflix does, and I’ve seen others do, is eliminate the tracking of vacation time. They hold people responsible for getting work done, and if you don’t do the work, you get to move on to another place of employment.

That got me thinking after following the debate about logic, mathematics and NULL in the SQLServerCentral forums. It’s a fascinating view in how some people look at NULL in databases, and worth reading.

I started to wonder what the proper value would be for these fields?

  • Netflix.VacationHoursAccrued
  • Netflix.VacationHoursUsed

Would you set them to 0? Or inifinity, maybe marked by something like 99999?

Or would you use NULL? With the idea that you don’t know, and more importantly to me, you don’t care? I think that the proper design would depend on what you plan to do with the data. It’s not being used, so my opinion is that NULL works fine, and the NULL bitmap could potentially use less space.

Comments

Posted by mtillman on 30 August 2010

Well, thank you Steve.  I'm glad that I decided to create that thread and I plan to spend more time on it when I can  later.  So stay tuned.  

I know some points I wanted to make with it, but its still partly a mystery (a NULL).  In other words, I don't really know where this will take us yet.  But that's one reason it's worth thinking about.

Posted by mtillman on 30 August 2010

As for answering your question, I would be afraid do overwrite anything in it for fear of management changing their minds and the history would be lost.

But of course that's beside the point of your post.  If we didn't have to worry about that, then I would probably opt for NULL since zero can cause errors with division.  Also, if any programs used the column for adding, then 99999 would cause issues too.  Good question.

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