title: When to create a new SQL Server Index?
body: <p>Obviously (methinks), creating an index on a <code>BIT</code> column is unnecessary. However, if you had a column that you need to search in which every value is likely unique, like <code>BlogPost</code> or <code>StreetAddress</code> or something, then an index seems appropriate (again, methinks).</p>
  
  <p>But what's the cutoff? What if you expect 10,000 rows and you'll have about 20 unique values among them. Should an index be created?</p>
  
  <p>Thanks in advance.</p>