Bug 200516 CachedQueryResults should also implement IQueryService.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
if ( ( dest.getInterval( ) != IGroupDefinition.NO_INTERVAL )
				&& ( dest.getIntervalRange( ) != 0 ) )
		{
			return new GroupComputedColumn( groupName,
					expr,
					QueryExecutorUtil.getTempComputedColumnType( interval ),
					GroupCalculatorFactory.getGroupCalculator( src.getInterval( ),
							getColumnDataType( cx, expr ),
							src.getIntervalStart( ),
							src.getIntervalRange( ) ) );
		}
		else
		{
			return new ComputedColumn( groupName,
					expr,
					QueryExecutorUtil.getTempComputedColumnType( interval ) );
		}
	}
	/**
	 * Populate the sortings in a query.
	 * 
	 * @throws DataException
	 */
	private void populateSorting( ) throws DataException
	{
		List sorts = this.baseQueryDefn.getSorts( );
		if ( sorts != null && !sorts.isEmpty( ) )
		{
			IQuery.SortSpec[] sortSpecs = new IQuery.SortSpec[sorts.size( )];
			Iterator it = sorts.iterator( );