public override List <long> GetIDList()
 {
     if (CachingPolicy == CachingPolicy.Dictionary)
     {
         RefreshCacheIfNeed();
     }
     if ((CachingPolicy != CachingPolicy.None) && (IsWholeCacheValid))
     {
         return(_cache.GetIDList());
     }
     return(base.GetIDList());
 }