title: Creating Indexes for Group By Fields?
body: <p>Do you need to create an index for fields of group by fields in an Oracle database?</p>
  
  <p>For example: </p>
  
  <pre><code>select * 
  from some_table
  where field_one is not null and field_two = ?
  group by field_three, field_four, field_five
  </code></pre>
  
  <p>I was testing the indexes I created for the above and the only relevant index for this query is an index created for field_two.  Other single-field or composite indexes created on any of the other fields will not be used for the above query.  Does this sound correct?</p>