Bug 182680 Use feature of new Aggregation framework of Data Engine.
DataEngine will implement new aggregation framework in 2.2.0RC0. After the implementation is finished Engine should go ahead to use new column bindings in definition of map/highlight.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/GetParameterDefinitionTask.java
* definition, prepare and execute the query. Cache the iterator of the
	 * result set and also cache the IBaseExpression used in the prepare.
	 * 
	 * @param parameterGroupName -
	 *            the cascading parameter group name
	 */
	public void evaluateQuery( String parameterGroupName )
	{
		CascadingParameterGroupHandle parameterGroup = getCascadingParameterGroup( parameterGroupName );
		if ( dataCache == null )
			dataCache = new HashMap( );
		if ( parameterGroup == null )
			return;
		
		
		IResultIterator iterOld = (IResultIterator) dataCache.get( parameterGroup.getName( ) );
		if ( iterOld != null )
		{
			dataCache.remove( parameterGroup.getName( ) );
			try
			{
				IQueryResults iresultOld = iterOld.getQueryResults();
				iterOld.close( );
				iresultOld.close( );
			}
			catch ( BirtException ex )
			{
				log.log( Level.WARNING, ex.getMessage( ) );
			}
		}