title: Querydsl - paging functionality
body: <p>It seems that in Jpa QueryDsl I can use paging like:</p>
  
  <pre><code>return new JPAQueryFactory(getEntityManager())
      .selectFrom(entity)
      .where(where_clause)
      .orderBy(order_by_clause)
      .offset(pageNumber * 20)
      .limit(20)
      .fetchResults();
  </code></pre>
  
  <p>Questions are:</p>
  
  <ul>
  <li>Is it optimal approach? Does fetchResults load only 20 elements from DB and make count query to get information about total number of entities which are in db?</li>
  <li>Or maybe there is some option like .page(2).limit(20)?</li>
  </ul>
  
  <p><em>Yes I know that Spring-Data has already Paging and interface for QueryDsl but because of the complicated "order by" clause which is not supported by Spring-Data I cannot use it :(</em></p>