title: Magento flat product
body: <p>when trying to enable and reindex Product Flat Data - getting error from magento</p>
  
  <blockquote>
    <p>The Flat Catalog module has a limit of 64 filterable and/or sortable
    attributes. Currently there are 521 of them. Please reduce the number
    of filterable/sortable attributes in order to use this module.</p>
  </blockquote>
  
  <p>I can't understand what this means and from where magento gets this values.
  In attributes I have only 321 different attributes so from where magento gets value of 521 currently used and where it takes limit for 64 of them???</p>
  
  <p>thnx.</p>