title: What is the reason for ORA-00054 error?
body: <p>From Oracle's documentation:-</p>
  
  <pre><code>ORA-00054 resource busy and acquire with NOWAIT specified   
  
    Cause: Resource interested is busy.
    Action: Retry if necessary. 
  </code></pre>
  
  <p>In our code we issue a <code>SELECT FOR UPDATE NOWAIT</code> command to lock the row we are about to update.</p>
  
  <p>Right now the logic is if it returns SQL error <code>54</code> then it is assumed that another user is trying to update that same record. Is this logic valid?</p>
  
  <p>From Oracle's documentation it looks more like if the DB is overwhelmed then this might also cause this error to be thrown.</p>
  
  <p>What are the possible reasons for this error, when we are only using the above SQL command?</p>