If I am reading this article (http://weblogs.sqlteam.com/peterl/archive/2010/07/02/Proper-Relational-Division-With-Sets.aspx) correctly, this solution should also be pretty fast:
WITH Target AS
(
SELECT Rate, Shift
FROM @T
WHERE Rate = @Rate
)
SELECT c.Rate
FROM
(
SELECT Rate, rc=COUNT(*)
FROM @T
GROUP BY Rate
) a
JOIN
(
SELECT rc=COUNT(*)
FROM Target
) b ON b.rc <= a.rc
JOIN @T AS c ON c.Rate = a.Rate
JOIN Target AS d ON d.Shift = c.Shift
GROUP BY c.Rate
HAVING COUNT(*) = MIN(b.rc);
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