title: MySQL server uses only 1 out of 48 CPU cores with GROUP BY queries
body: <p>I have high end 48 CPU core server with latest MySQL 5.7 installed</p>
  
  <p>I'm bit surprised that when executing queries with GROUP BY, no matter how I format my query I get only 1 CPU core used for that query, clearly illustrated by htop output</p>
  
  <p>Of course I can perform multiple queries at the same time, and that's how I can use all the cores but it seems not too convenient and not every query can be split to use full server's power</p>
  
  <p>Are there any MySQL extensions or SQL hints that allow to use multiple cores while processing data with GROUP BY?</p>