title: Any way to select without causing locking in MySQL?
body: <p>Query:</p>
  
  <pre><code>SELECT COUNT(online.account_id) cnt from online;
  </code></pre>
  
  <p>But online table is also modified by an event, so frequently I can see lock by running <code>show processlist</code>.</p>
  
  <p>Is there any grammar in MySQL that can make select statement not causing locks?</p>
  
  <p>And I've forgotten to mention above that it's on a MySQL slave database.</p>
  
  <p>After I added into <code>my.cnf:transaction-isolation = READ-UNCOMMITTED</code>
  the slave will meet with error:</p>
  
  <blockquote>
    <p>Error 'Binary logging not possible. Message: Transaction level 'READ-UNCOMMITTED' in InnoDB is not safe for binlog mode 'STATEMENT'' on query</p>
  </blockquote>
  
  <p>So, is there a compatible way to do this?</p>