message: issue enable string copy  for sort iteratrion
diff: @@ -226,7 +226,7 @@ namespace ardb
  Iterator* iter = m_engine->Find(ctx, startkey);
  while (iter->Valid())
  {
  - KeyObject& k = iter->Key();
  + KeyObject& k = iter->Key(true);
  if (k.GetType() != startkey.GetType() || k.GetNameSpace() != startkey.GetNameSpace() || k.GetKey() != startkey.GetKey())
  {
  break;
  @@ -261,12 +261,11 @@ namespace ardb
  }
  DELETE(iter);
  }
  -
  if (!options.nosort)
  - {
  - for (size_t i = 0; i < sortvals.size(); i++)
  {
  if (NULL != options.by)
  + {
  + for (size_t i = 0; i < sortvals.size(); i++)
  {
  if (GetValueByPattern(ctx, options.by, sortvals[i].value, sortvals[i].weight) < 0)
  {
  