title: MySQL execute 2 queries to the same table simultaneously
body: <p>New values are added to a MySQL Database all day long.  There are over 8 million rows in this table.  Because there are a lot of old values, I want to clean these up without stopping the Java Program Inserting the values.</p>
  
  <p>I am sending this query to the MySQL:</p>
  
  <pre><code>DELETE FROM `tablename`
  WHERE `from` &lt;= (date_add(now(), interval -20 DAY))
  </code></pre>
  
  <p>but what happens is that the Java Program stops adding new values to the table.  It there any way I can handle this without editing the Java Program?
  I would be willing to run the query as a cronjob once a day.</p>
  
  <p>I have also tried working with the parameter LOW_PRIORITY, but it doesn't make any difference.</p>