title: Slow query in Mysql
body: <p>I have the following slow query. cid and date are both index in each tables. There are 1M rows in each table. I need all columns in those three tables</p>
  
  <pre><code> select * from 
      (SELECT * FROM `table1` where `cid` =? order by date desc limit 0, 10) as a 
          left join ( SELECT * FROM `table2` where `cid?` =?) as b on a.date=b.date? 
          left join (SELECT * FROM `table3` where `cid` =? ) as c on a.date=c.date? 
          order by date asc
  </code></pre>
  
  <p>Any suggestions how to improve the query?</p>