public RexNode right() {
      return rightChildPredicates;
    }
The PullUp Strategy is sound but not complete.
<ol>
<li>We only pullUp inferred predicates for now. Pulling up existing
predicates causes an explosion of duplicates. The existing predicates are
pushed back down as new predicates. Once we have rules to eliminate
duplicate Filter conditions, we should pullUp all predicates.
<li>For Left Outer: we infer new predicates from the left and set them as
applicable on the Right side. No predicates are pulledUp.
<li>Right Outer Joins are handled in an analogous manner.
<li>For Full Outer Joins no predicates are pulledUp or inferred.
</ol>
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/stats/HiveRelMdPredicates.java