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/PreparedDataSourceQuery.java
return;
		
		Collection parameterHints = null;
		
		IBaseDataSourceDesign dataSourceDesign = null;
		DataSourceRuntime dsRuntime = this.dataEngine.getDataSourceRuntime( dataSetDesign.getDataSourceName( ) );
		if ( dsRuntime != null )
		{
			dataSourceDesign = dsRuntime.getDesign( );
			DataSetRuntime dataSet = DataSetRuntime.newInstance( dataSetDesign,
					null );
			parameterHints = new ParameterUtil( null,
					dataSet,
					this.queryDefn,
					scope ).resolveDataSetParameters( true );
		}
		getDataSetCacheManager( )
				.setDataSourceAndDataSet( dataSourceDesign,
						dataSetDesign,
						parameterHints,
						this.appContext);
		if ( DataSetCacheUtil.getCacheOption( dataEngine.getContext( ), appContext ) == DataEngineContext.CACHE_USE_ALWAYS )
		{
			getDataSetCacheManager( )
					.setAlwaysCacheRowCount( DataSetCacheUtil.getCacheCount( dataEngine.getContext( ), appContext ));
		}
		getDataSetCacheManager( )
				.setCacheOption( DataSetCacheUtil.getCacheOption( dataEngine.getContext( ),
						appContext ) );
	}