Bug 180189 Support in memory data set cache.
Currently, Design-Time Data Cache is stored on disks. By performance tests using ramdisk, we found that caching in physical memory can improve the performance of RunAndRender by 30%.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedJointDataSourceQuery.java
preparedQuery );
			}
			IResultIterator ri = preparedQuery.execute( null )
					.getResultIterator( );
			assert ri instanceof ResultIterator;
			return (ResultIterator) ri;
		}
		catch ( BirtException e )
		{
			throw DataException.wrap(e);
		}
	}
	/**
	 * 
	 * @param dataEngine
	 * @param dataSetDesignName
	 * @param isLeftDataSet
	 * @param queryDefinition
	 * @throws DataException 
	 */
	private void setParameterBindings( DataEngineImpl dataEngine, String dataSetDesignName, boolean isLeftDataSet, QueryDefinition queryDefinition ) throws DataException
	{
		IBaseDataSetDesign dataSetDesign = dataEngine.getDataSetDesign( dataSetDesignName );
		if( dataSetDesign == null )
		{
			throw new DataException( ResourceConstants.UNDEFINED_DATA_SET, dataSetDesignName );
		}
		Iterator it = dataSetDesign.getParameters( ).iterator( );
		if ( it.hasNext( ) )
		{