public Set<Integer> getProjsFromRightPartOfJoinKeysInChildSchema() {
      assert projsJoinKeysInChildSchema.size() == 2;
      return this.projsJoinKeysInChildSchema.get(1);
    }
JoinPredicateInfo represents Join condition; JoinPredicate Info uses
JoinLeafPredicateInfo to represent individual conjunctive elements in the
predicate.<br>
JoinPredicateInfo = JoinLeafPredicateInfo1 and JoinLeafPredicateInfo2...<br>
<p>
JoinPredicateInfo:<br>
1. preserves the order of conjuctive elements for
equi-join(equiJoinPredicateElements)<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>
3. Keeps a map of projection indexes that are part of join keys to list of
conjuctive elements(JoinLeafPredicateInfo) that uses them.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/HiveCalciteUtil.java