Archive Database Step 11: Measure, Then Index

Take the three queries you run most often against your schema and get the plan for each. Write down which do a SCAN and on which table. Add the indexes you believe will help, one at a time, and get the plan again after each. Record which ones actually changed the plan and which did not, and remove the indexes that made no difference. An index that changed nothing is pure cost, and being willing to delete it is the part of this that most people skip.