title: mysql, ifnull vs coalesce, which is faster?
body: <p>if it's known that there are only two values to candidate for the result of a column,</p>
  
  <pre><code>ifnull(a, b) as a_or_b_1
  </code></pre>
  
  <p>and</p>
  
  <pre><code>coalesce(a, b) as a_or_b_2
  </code></pre>
  
  <p>will give the same result. but which is faster? when searching i found <a href="http://www.doinglines.com/">this article</a>, which says <strong>ifnull</strong> is faster. but it was the only article i found. any views on this?</p>
  
  <p>thanks in advance :)</p>