Hi amir sherafatian,
Yes you are right, these kind of queries are not fully processed on the database server in the current official version of OpenAccess. However there have been a lot of Linq improvements on our product lately and pushing Min,Max,Count etc. to the server are part of those. You will be able to use this functionality as soon as the next official OpenAccess release or internal build. Thank you for your patience.
the Telerik team