Bug 132805 Set descending to outer group will affect inner group.
Description: Set descending to outer group will affect inner group. Steps to reproduce: 1. New a sample datasource and dataset from orders. 2. Drag the dataset to Layout. 3. Add a group on ordernumber, interval 10, descending. 4. Add another group on orderdate, interval day 2, ascending. 5. Preview. Expected result: Data are grouped correctly. Actual result: Inner group didn't work unless you set outer group's sort to asc.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/QueryExecutor.java
this.baseQueryDefn = baseQueryDefn;
		this.aggrTable = aggrTable;
	}
	
	/**
	 * Provide the actual DataSourceRuntime used for the query.
	 * 
	 * @return
	 */
	abstract protected DataSourceRuntime findDataSource( )
			throws DataException;
	/**
	 * Create a new instance of data set runtime
	 * 
	 * @return
	 */
	abstract protected DataSetRuntime newDataSetRuntime( )
			throws DataException;
	
	/**
	 * Create a new unopened odiDataSource given the data source runtime
	 * definition
	 * 
	 * @return
	 */
	abstract protected IDataSource createOdiDataSource( )
			throws DataException;
	
	/**
	 * Create an empty instance of odi query