title: RavendB: Select and GroupBy - cannot use Map/Reduce Index
body: <p>I've got following data structure.</p>
  
  <pre><code>public class Usage
  {
    public string Id { get; set;}
    public string CatalogNumber { get; set;}
    public string ProductDescription { get; set;}
    public string ProductType { get; set;}
    public DateTime DeliveryDate { get; set;}
    public int AmountSold { get; set;}
  }
  </code></pre>
  
  <p>I would like to have the result grouped by {CatalogNumber}, {ProductDescription}, {ProductType} within a specific {DeliveryDate}</p>
  
  <p>ie. I'd like to query the total amount sold for a specific product within 2013-01-01 to 2013-04-04.</p>
  
  <p>Expected result:</p>
  
  <pre><code>{
    {
      CatalogNumer: 12345
      ProductDescription: Product1
      ProductType: TV
      TotalAmountSold: 125
    }
  {
      CatalogNumer: 8797
      ProductDescription: Product2
      ProductType: Fridge
      TotalAmountSold: 13
    }
  }
  </code></pre>
  
  <p>Unfortunately I cannot use a Map/Reduce index because there's no way to pass parameters to the index.</p>
  
  <p>Any ideas?</p>