title: How to see which MySQL partitions are chosen?
body: <p>I'm running a query against a partitions table but the performance is terrible.
  I have a feeling that it is doing a full table scan instead of just a scan of two or three partitions.
  The partition key is in the where clause.</p>
  
  <p>Is there a way I can check what partitions it looked at to answer the query?
  Is there an EXPLAIN that could tell me which partitions it will use?</p>
  
  <p>Any tips for using partitions in JOINs?</p>
  
  <p>I'm using MySQL 5.6.11</p>
  
  <p>Thanks</p>