private boolean isClosedBound(GenericUDF udf) {
      return udf instanceof GenericUDFOPEqualOrGreaterThan ||
          udf instanceof GenericUDFOPEqualOrLessThan;
    }
removes all values which are outside of the scope of the column
ql/src/java/org/apache/hadoop/hive/ql/optimizer/stats/annotation/StatsRulesProcFactory.java