With thousands of users trying to modify the exact same row, SQL must do them one at a time, pausing the others until those before it complete.  Otherwise, of course,...

A covering index is an index that has all the columns needed to satisfy, or "cover", a given query.

For example, say I have a table with 20 columns,...

1) You didn't strip the time.
2) You need to use < the ending day, rather than <=

For example:

I've changed it to:
(DateAttribute >= DATEADD(DAY,-10,CAST(GETDATE() AS...

Since you already have an identity column, go ahead and add that to make the clustering unique.  SQL would "uniquify" it, but it's better to do it yourself to avoid...

Change the clustering index to the 2 columns that are used most often / nearly always as predicates.  If you prefer, you can add a unique column as a 3rd...

Some things to consider:

Typically you'll most likely access these rows by datetime range.  I'm guessing the actual query might even have such a date restriction, or, if it...