@Override
  public RowSet fetchResults(OperationHandle opHandle, FetchOrientation orientation,
                             long maxRows, FetchType fetchType) throws HiveSQLException {
    RowSet rowSet = sessionManager.getOperationManager().getOperation(opHandle)
        .getParentSession().fetchResults(opHandle, orientation, maxRows, fetchType);
    LOG.debug(opHandle + ": fetchResults()");
    return rowSet;
  }
If this is a background operation run asynchronously,
we block for a duration determined by a step function, before we return
However, if the background operation is complete, we return immediately.
service/src/java/org/apache/hive/service/cli/CLIService.java