Hi,
I have an OUTER APPLY in my query.
When I run the query without including the OUTER APPLY columns in the main SELECT the performance is good.
For example, in following query I am not including any of the columns from X.
SELECT U.UserID,
U.FirstName
FROM Users U
OUTER APPLY (SELECT TOP 1
Salary,
Currency,
Interest
FROM Salary S
WHERE S.UserID = U.UserID
AND S.PaymentDate = U.StartDate) X
When I include even a single column from the OUTER APPLY the performance slows down.
SELECT U.UserID,
U.FirstName,
X.Salary
FROM Users U
OUTER APPLY (SELECT TOP 1
Salary,
Currency,
Interest
FROM Salary S
WHERE S.UserID = U.UserID
AND S.PaymentDate = U.StartDate) X
Does anybody have an idea why this might be happening?
Thanks,
Ben
