@Override
  String fixCtasColumnName(String colName) {
    if (runCBO) {
      int lastDot = colName.lastIndexOf('.');
      if (lastDot < 0)
       {
        return colName; // alias is not fully qualified
      }
      String nqColumnName = colName.substring(lastDot + 1);
      STATIC_LOG.debug("Replacing " + colName + " (produced by CBO) by " + nqColumnName);
      return nqColumnName;
    }

    return super.fixCtasColumnName(colName);
  }
Checks whether Calcite can handle the query.

@param queryProperties
@param conf
@param topLevelQB
         Does QB corresponds to top most query block?
@return null if the query can be handled; non-null reason string if it
        cannot be.

        Assumption:<br>
        1. If top level QB is query then everything below it must also be
        Query<br>
        2. Nested Subquery will return false for qbToChk.getIsQuery()
ql/src/java/org/apache/hadoop/hive/ql/parse/CalcitePlanner.java