private static ColumnInfo getColumnInfoForColumn(String neededCol, List<ColumnInfo> schema) {
    for (ColumnInfo ci : schema) {
      if (ci.getInternalName().equalsIgnoreCase(neededCol)) {
        return ci;
      }
    }
    return null;
  }
Scale selectivity based on key range ratio.
@param csPK - column statistics of primary key
@param csFK - column statistics of potential foreign key
@return
ql/src/java/org/apache/hadoop/hive/ql/stats/StatsUtils.java