* The relational expression is already in leaf-join-form, per
* {@link #toLeafJoinForm(org.eigenbase.rel.RelNode)}.
*/
public static RelNode tryUseStar(RelNode rel,
final RelOptTable starRelOptTable) {
final StarTable starTable = starRelOptTable.unwrap(StarTable.class);
assert starTable != null;
RelNode rel2 = rel.accept(
new RelShuttleImpl() {
@Override
public RelNode visit(TableAccessRelBase scan) {