rmechaber (10/28/2013)
Thanks Dwain.c.No, I don't see the behavior being at odds with BOL either, but I do see it being at odds with computational integrity and statistics. And BOL has a serious omission that doesn't explain this at all.
How can you compute a rank of NULL values? Why put all the NULL values at the bottom of the list when ordering to compute NTILE()? You could just as easily put them all at the top or scattered through the middle or lumped into the N'th tile where N is the day number of the week or.... OK, I do see that putting them all at the bottom is behavior that is repeatable and predictable. But it's very much like saying that the median salary of your survey's population was $0.00 b/c 51% of the survey respondents didn't provide any salary information in their answers.
Thanks,
Rich
I did say that "I agree that the behavior seems unusual" and I'll go further to say that your contention about the statistical significance of the NULLs is correct. You do always have the option to eliminate the NULLs with a WHERE clause, but obviously that doesn't change the counter-intuitive nature of Microsoft's implementation decision.
My thought question: Have you ever been told that your query runs too fast?
My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.
Need to UNPIVOT? Why not CROSS APPLY VALUES instead?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
[url url=http://www.sqlservercentral.com/articles/St