title: Performance Tuning: Create index for boolean column
body: <p>I have written a daemon processor which will fetch rows from one database and insert them into another for synchronizing. It will fetch rows based on a <code>boolean</code> indication flag <code>sync_done</code>.</p>
  
  <p>My table has hundreds of thousands of rows. When I select all rows with  <code>sync_done is false</code>, will it cause any database performance issues? Should I apply indexing for that <code>sync_done</code> column to improve performance, since only rows with a <code>sync_done</code> value of <code>false</code> are fetched?</p>
  
  <p>Say, I have 10000 rows. Of those, 9500 have already been synchronized (<code>sync_done is true</code>) and will not be selected.</p>
  
  <p>Please suggest how I might proceed.</p>