public static boolean limitRelNode(RelNode rel) {
    if ((rel instanceof Sort) && ((Sort) rel).fetch != null) {
      return true;
    }

    return false;
  }
JoinLeafPredicateInfo represents leaf predicate in Join condition
(conjuctive lement).<br>
<p>
JoinLeafPredicateInfo:<br>
1. Stores list of expressions from left and right child which is part of
equi join keys.<br>
2. Stores set of projection indexes from left and right child which is part
of equi join keys; the indexes are both in child and Join node schema.<br>
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/HiveCalciteUtil.java