title: How effective is creating index on column having two types of values only
body: <p>I have created an index on a column, which has only two possible values (Y and N), data type is same for both values.</p>
  
  <p>Suppose column name is indicator.
  I wrote a select statement like,</p>
  
  <pre><code>SELECT INDICATOR 
  FROM TEMP_TABLE 
  ORDER BY INDICATOR
  </code></pre>
  
  <p>When I used explain plan for this query in SQL developer, it is using full table scan not index scan.</p>
  
  <p>Why it is not using index table scan.</p>