Thanks for your assistance it is very helpful , you say that the view is created in tempdb and it can have a heavy impact ,so each time the view is accessed how is the view "rebuilt" does it leave the 20 million records in the tempdb and add extra records to the view or keep it in memory or is it recreated from scratch each time or maybe left in buffer if sufficient memory is available (where is the information contained in the view held and how is it processed?) , what I am trying to understand is the process that sql uses to retrieve the information/update the information /and return the information . Thanks again for your help in this