docs: @Override
      public String readSingle(String key) throws Exception {
          BoundStatement bStmt = readPstmt.bind();
          bStmt.setString("\"_id\"", key);
          bStmt.setConsistencyLevel(this.ReadConsistencyLevel);
          ResultSet rs = session.execute(bStmt);
  
          List<Row> result=rs.all();
          if (!result.isEmpty())
          {
              if (result.size() != 1) {
                  throw new Exception("Num Cols returned not ok " + result.size());
              }
          }
          else {
              return CacheMiss;
          }
  
          return ResultOK;
      }