title: Should I COUNT(*) or not?
body: <p>I know it's generally a bad idea to do queries like this:</p>
  
  <pre><code>SELECT * FROM `group_relations`
  </code></pre>
  
  <p>But when I just want the count, should I go for this query since that allows the table to change but still yields the same results.</p>
  
  <pre><code>SELECT COUNT(*) FROM `group_relations`
  </code></pre>
  
  <p>Or the more specfic</p>
  
  <pre><code>SELECT COUNT(`group_id`) FROM `group_relations`
  </code></pre>
  
  <p>I have a feeling the latter could potentially be faster, but are there any other things to consider?</p>
  
  <p><strong>Update</strong>: I am using InnoDB in this case, sorry for not being more specific.</p>