Why is doing a top(1) on an indexed column in SQL Server slow?
- by reinier
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 where the campaignid is indeed 3835
For all these rows, the connectionid is the same.
I just want to find out this connectionid.
use messaging_db;
SELECT TOP (1) connectionid
FROM…