Optimise/Tuning

Execution Plan

Make sure you have selected Query, Include Actual Execution Plan (or press the button on the tool bar).

When you run the query an extra tab will be displayed showing the Execution Plan.

Understanding the Execution Plan

Index Seek Vs. Index Scan (Table Scan) (PDF):

../../../misc/howto/microsoft/sql-server/sql-server-index-seek-vs-index-scan-table-scan.pdf

Copy of blog entry by Pinal Dave

Union

…change UNION in the view to UNION ALL. SQL does extra processing when you do UNION to ensure the rows returned are unique. As we know they are unique we can use UNION ALL.