November 10, 2006 at 9:09 am
I am performing a review of all indexes on a database and have a question concerning the data returned by DBCC_SHOWSTATISTICS. I know that the density column is an indication of selectivity: the lower the density, the higher the selectivity of the index. So, a value such as 4.38347509E-5 would suggest that the index is highly selective and, as such, is a useful index. But what does a density of 0.00 mean? Is this a very highly select index, or is this an index that has very little, if any selectivity at all?
Gordon Pollokoff
"Wile E. is my reality, Bugs Bunny is my goal" - Chuck Jones
November 14, 2006 at 3:01 am
count the distinct values in the index row and compare to the rows in the table - if they match the index is highly selective, the bigger the difference the less selective the index is.
[font="Comic Sans MS"]The GrumpyOldDBA[/font]
www.grumpyolddba.co.uk
http://sqlblogcasts.com/blogs/grumpyolddba/
Viewing 2 posts - 1 through 2 (of 2 total)
You must be logged in to reply to this topic. Login to reply