Learn T-SQL Querying

Key Lookups

A Key Lookup operator represents a lookup from a non-clustered index into a clustered index. It is effectively a clustered index seek.

The following example shows a query executed in the AdventureWorks sample database with a Key Lookup:

SELECT *FROM Person.PersonWHERE LastName = N'Maxwell';

The query generates the following execution plan:

Notice how the key lookup is joined to the non-clustered index seek in the same manner a the RID Lookup.