解决EF 4.0 中数据缓存机制

 public IQueryable<T> LoadEntities(Func<T, bool> whereLambda)
        {
            try
            {
                var set = _db.CreateObjectSet<T>();
                set.MergeOption = MergeOption.OverwriteChanges;
                var entities = set.Where<T>(whereLambda).AsQueryable();

                //var entities = _db.CreateObjectSet<T>().Where<T>(whereLambda).AsQueryable();

                return entities;
            }
            catch (Exception ex)
            {
                Logger.Error("LoadEntities Error！", ex);
                throw new Exception("LoadEntities Fail", ex);
            }
        }