public void setJoinRemovalFactor(int dimIdx, int factIdx) {
    joinRemovalFactors[dimIdx] = factIdx;
  }
Indicates that a dimension factor's join can be removed because of a
semijoin with a fact table.

@param dimIdx Dimension factor
@param factIdx Fact factor
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/rules/HiveLoptMultiJoin.java