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
List obList = new ArrayList( );
			for ( int i = 0; i < obs.length; i++ )
				obList.add( obs[i] );
			return obList;
		}
		/**
		 * @return
		 */
		private boolean doesLoadFromCache( )
		{
			PreparedJointDataSourceQuery self = PreparedJointDataSourceQuery.this;
			return getDataSetCacheManager()
					.doesLoadFromCache( null,
							dataSetDesign,
							null,
							appContext,
							DataSetCacheUtil.getCacheOption( self.dataEngine.getContext( ),
									appContext ),
							DataSetCacheUtil.getCacheCount( self.dataEngine.getContext( ), appContext ));
		}
		/**
		 * @return
		 */
		private boolean doesSaveToCache( )
		{
			return getDataSetCacheManager().doesSaveToCache( );
		}
	}
}