Hi Martin > btw. the feature cache from #3200 is based on R-tree.
Wow, cool! One question to the feature cache patch (didn't yet look into the code in detail, so maybe a silly one): Reading the usage notes of the QgsFeatureCache class, it seems to me the implemented strategies are optimised for desktop scenario where user loads a scene and then zooms in. In a wms server scenario, it would be nice to cache features in the tiles most viewed by visitors (e.g. parts of the city rather than countryside), but the zoom-in scenario is less likely in a webgis. Is the code in the patch already optimised for the web-scenario or is it necessary to implement a new mode/strategy? Regards, Marco + * Last currently implemented mode/strategy is called "heuristics". This strategy + * compares the currently cached region with the requested one - and in case its + * much bigger, the cached area is downsized to free it's (probably) unused parts. + * This heuristics is based on the idea that user mostly starts editing with a big + * map and he zooms-in afterwards, editing only a small part of the whole map. + * This means he mostly doesn't need all the data in memory... Am Dienstag, 1. November 2011, 14.50:20 schrieb Martin Dobias: > On Tue, Nov 1, 2011 at 9:38 AM, Marco Hugentobler > > <marco.hugentob...@sourcepole.ch> wrote: > >> > Martin I just found that you proposed a patch to allow speed up vector > >> > rendering > >> > > >> > http://hub.qgis.org/issues/3200 > >> > > >> > maybe this can be tested again and added in time for 1.8? > >> > >> Giovanni, > >> porting and testing the patch would need quite a lot of time. > >> Definitely not something that could be released soon. > > > > A propos feature caching: there was an interesting presentation at foss4g > > 2007 about feature caching: > > > > http://2007.foss4g.org/presentations/viewattachment.php?attachment_id=131 > > > > The idea to use r-Tree entities as data blocks sounds reasonable. Would > > be cool to have something like this in QGIS. > > Hi Marco > > btw. the feature cache from #3200 is based on R-tree. > > Martin -- Dr. Marco Hugentobler Sourcepole - Linux & Open Source Solutions Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland marco.hugentob...@sourcepole.ch http://www.sourcepole.ch Technical Advisor QGIS Project Steering Committee _______________________________________________ Qgis-developer mailing list Qgis-developer@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-developer
