title: SQL Server Performance Comparison Between Over Partition By And Group By
body: <p>Although a couple of questions were already posted in SO about the difference between <code>Over Partition By</code> and <code>Group By</code>, I did not find a definitive conclusion about which performs better.</p>
  
  <p>I set up a <a href="http://sqlfiddle.com/#!3/91591/1/0" rel="noreferrer">simple scenario at SqlFiddle</a>, where <code>Over (Partition By)</code> seems to boast a better execution plan (I am not much familiar with them, however).</p>
  
  <p>Is the amount of data in the tables supposed to change this? Does <code>Over (Partition By)</code> then ultimately performs better?</p>
  
  <p><a href="https://i.stack.imgur.com/xJP6T.png" rel="noreferrer"><img src="https://i.stack.imgur.com/xJP6T.png" alt="enter image description here"></a></p>
  
  <p><a href="https://i.stack.imgur.com/Woy19.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Woy19.png" alt="enter image description here"></a></p>