GilaMonster (9/26/2013)
Primary purpose of an index is to reduce the number of rows in consideration for a query as early as possible. Which reduces row count, a filter or a join?
Another question on the same line. I have a clustered index on two columns C1 accepts NULL and C2 doesn't. Now in my nc index when i dont include C2 it is still using the right index, but when i dont include c1 it is not using the right index. Is it because c1 has null values?