Thanks Grant for your reply.

Actually I am never created statistics on table but in my company someone told me to create and work on statistics it will help you a lot to speed up query.As I am working on PDW I don't know how to create it in PDW because in PDW we don't have primary and foreign keys structure. We have distributed and replicate structure within nodes in PDW. That's why I was collecting information on internet to create and update statistics on our tables.

I read your links and those really helped me a lot. I will look forward to works with statistics in PDW.

Thanks once again.