no data records in index <str>

  Explanation:  A null dbkey was found as  the  root  dbkey  of  a
  B-tree  index.   It  is assumed that there are no records in the
  relation, and hence, the root dbkey is null.

  User Action:  If you know there are records in the relation, the
  index  is  corrupt, and you may rebuild the index.  If there are
  no  records  in  the  index,  however,  this  is  not  an  error
  condition.