title: Index on UNION query?
body: <p>i've got this union query:</p>
  
  <pre><code>(SELECT INSTALLER, INSTALLTIME, RESULT, JOBNUMBER, HONAME, ADDRESS, CITY, STATE, ZIP, NOTES, SMNOTES, '' as priority, PAFS, upsell, TERM, MMRUPGRADE, WARRANTY, EFT FROM ACCOUNTS 
  WHERE INSTALLDATE = '$date' &amp;&amp; FUNDINGSTATUS !='DEAD') 
  UNION 
  (SELECT technician, servicetime, result, ID, Customername, address, city, state, zip, notes, board, priority, '', '', '', '', '', '' FROM service 
  WHERE serviceday = '$date') 
  ORDER BY INSTALLER, priority
  </code></pre>
  
  <p>i'm curious if putting an index on the date field will help speed up both queries? or will the fact that i use FUNDINGSTATUS in the first where clause will make that query not utilize the index?</p>