求大神 说明一下ef ObjectContext 与DBContext 差别，为何我自己继承DBContext 写的类的查询Max始终把整个表数据查询出来！而那种Model.edmx 不会！

如果用Model.edmx 写分页查询，生成的sql 会分页，但是用DBContext、或者DBSet 写分页 生成的sql 是自己查询整个表数据然后再 分页。。。

public class PersonRepository : GenericRepository<Person>, IPersonRepository
{
public PersonRepository(DbContext context)
: base(context)
{

}

public override IEnumerable<Person> GetAll()
{

return _entities.Set<Person>();
//return _entities.Set<Person>().Include(x => x.Country).AsEnumerable();
} 

}

public class PersonService : EntityService<Person>, IPersonService
{
IUnitOfWork _unitOfWork;
IPersonRepository _personRepository;

public PersonService(IUnitOfWork unitOfWork, IPersonRepository personRepository)
: base(unitOfWork, personRepository)
{
_unitOfWork = unitOfWork;
_personRepository = personRepository;
}

public PagedList<Person> PageList(int pageIndex, int pageSize)
{
var list = _personRepository.GetAll().Take(50).ToList();
//var newlist= list.ToPagedList<Person>(pageIndex, pageSize);

Console.WriteLine(DateTime.Now);
var max = _personRepository.Max();
Console.WriteLine(DateTime.Now);
var newlist = (from a in list select a).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();
var dd = list.Max(m => m.Id);
var totalcount = list.Count();
return new PagedList<Person>(newlist, totalcount, pageIndex, pageSize);
}
}

但是查看数据库监控