Bug 202038 errors occurred when preview the attached design file.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/pass/ResultSetProcessUtil.java
populator.getExpressionProcessor( ).clear( );
		computedColumnHelper.setModel( TransformationConstants.NONE_MODEL );
		
		
		
		
		
		
		cleanTempColumns( );
	}
	/**
	 * Clean the temporary data.
	 * 
	 * @throws DataException
	 */
	private void cleanTempColumns( ) throws DataException
	{
		IResultClass newMeta = rebuildResultClass( populator.getResultSetMetadata( ) );
		populator.setResultSetMetadata( newMeta );
		populator.getCache( ).setResultClass( newMeta );
		/*PassUtil.pass( populator,
				new OdiResultSetWrapper( populator.getResultIterator( ) ),
				false, session );
		populator.getCache( ).reset( );
		populator.getCache( ).next( );
		populator.getGroupProcessorManager( )
				.getGroupCalculationUtil( )
				.getGroupInformationUtil( )
				.setLeaveGroupIndex( 0 );*/
	}