Bug 131011 Support running query based on report document data
Data Engine should support running a query based on data set and expression data stored in a report document. This bugzilla entry serves as a repository for design docs and notes related to this feature.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/group/GroupBy.java
{
	private int columnIndex;
	private String columnName;
	private GroupSpec groupSpec;
	/**
	 * Static method to create and instance of subclass of GroupBy, based on the
	 * group definition
	 * 
	 * @param groupDefn
	 * @param columnIndex
	 * @param columnType
	 * @return GroupBy
	 * @throws DataException
	 */
	static GroupBy newInstance( GroupSpec groupDefn, int columnIndex, String columnName,
			Class columnType ) throws DataException
	{
		assert groupDefn != null;
		GroupBy groupBy = null;
		switch ( groupDefn.getInterval( ) )
		{