Bug 214196 [Automation][Compatibility]Exception occurs when preview a old crosstab with measure sorting
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/DataEngineImpl.java
e );
				throw e;
			}
		}
		dataSetDesigns.put( name, dataSet );
		logger.exiting( DataEngineImpl.class.getName( ), "defineDataSet" );
	}
	/*
	 * @see org.eclipse.birt.data.engine.api.DataEngine#clearCache(org.eclipse.birt.data.engine.api.IBaseDataSourceDesign,
	 *      org.eclipse.birt.data.engine.api.IBaseDataSetDesign)
	 */
	public void clearCache( IBaseDataSourceDesign dataSource,
			IBaseDataSetDesign dataSet ) throws BirtException
	{
		if ( dataSource == null || dataSet == null )
			return;
		DataSetCacheManager dscManager = this.getSession( ).getDataSetCacheManager( );
		if( dscManager == null )
			return;
		else
			dscManager.clearCache( dataSource, dataSet );
	}
	
	/**
	 * Returns the runtime defn of a data source. If data source is not found,
	 * returns null.
	 */
	DataSourceRuntime getDataSourceRuntime( String name )
	{
		return (DataSourceRuntime) dataSources.get( name );