public boolean isUnknown() {
    return Double.isInfinite(getRowCount())
        || Double.isInfinite(getRate())
        || Double.isInfinite(getWindow());
  }
@Test
  public void testKnownRel() {
    String sql = " select * from ORDER_DETAILS1 ";
    RelNode root = env.parseQuery(sql);
    NodeStats nodeStats =
        root.metadata(NodeStatsMetadata.class, root.getCluster().getMetadataQuery()).getNodeStats();
    Assert.assertFalse(nodeStats.isUnknown());
  }