public void stripVirtualColumn(VirtualColumn vc) {
    for (Map.Entry<String, Collection<ColumnAccess>> e : tableToColumnAccessMap.asMap().entrySet()) {
      for (ColumnAccess columnAccess : e.getValue()) {
        if (vc.getName().equalsIgnoreCase(columnAccess.columnName)) {
          e.getValue().remove(columnAccess);
          break;
        }
      }
    }
  }
Strip a virtual column out of the set of columns.  This is useful in cases where we do not
want to be checking against the user reading virtual columns, namely update and delete.
@param vc
ql/src/java/org/apache/hadoop/hive/ql/parse/ColumnAccessInfo.java