Why is doing a top(1) on an indexed column in SQL Server slow?

Question

I\'m puzzled by the following. I have a DB with around 10 million rows, and (among other indices) on 1 column (campaignid_int) is an index.

Now I have 700k rows wher

Answer 1

This doesn't answer your question, but try using:

SET ROWCOUNT 1
SELECT     connectionid
 FROM         outgoing_messages WITH (NOLOCK)
 WHERE     (campaignid_int = 3835)

I've seen top(x) perform very badly in certain situations as well. I'm sure it's doing a full table scan. Perhaps your index on that particular column needs to be rebuilt? The above is worth a try, however.