Why is my SQL Server ORDER BY slow despite the ordered column being indexed?

Question

I have an SQL query (generated by LINQ to Entities) which is roughly like the following:

SELECT * FROM [mydb].[dbo].[employees]
JOIN [mydb].[dbo].[industry]
         


        

Answer 1

What order are the fields in the clustered index included in? You'll want to put the startDateTime field first in order for the ORDER BY to match it, or in this case (countryId, startDateTime) up front in that order since you want to select a single countryId (indirectly, via countryName) and then order by startDateTime.