Steve I was pursuing the performance issue on the pmapper mailing list too. It transpires it is related to browser performance (from a JS aspect) for the web apps query/redraw processes -> IE7 - awful (>8mins), IE8 and FF pretty good - around 20secs for returning/highlighting 5000 features (and building results table) and Chrome about 13 secs, that is without even creating a spatial index. Thanks for the info and I think I may even not have to go down the db route (which keeps life simple!) just advise IE6/7 users to switch browsers (not the first webGIS app I know that does this....!)
Thanks Chris. On 25 August 2010 18:08, Lime, Steve D (DNR) <steve.l...@state.mn.us> wrote: > Like with everything it depends… Selection of features via a bounding > box shouldn’t be much, or really any, slower than drawing since it’s > basically the same mechanism for both. Attribute queries can be quite slow > with shapefiles since MapServer doesn’t do any attribute indexing. That’s > where the RDMS really adds value. There shouldn’t be much of a difference > with a bbox query, and in fact, a local shapefile will probably be faster, > even on larger datasets as long as you’ve build an spatial index file. > > > > Anyway, it’s what you do with results afterwards that matters and that’s > probably specific to your application. I’ve used query files to persist > selected features over many map draws successfully on modest (50,000 > feature) sized shapefiles. > > > > Steve > > > > *From:* Chris Jackson [mailto:webturt...@gmail.com] > *Sent:* Tuesday, August 24, 2010 10:34 AM > *To:* Lime, Steve D (DNR) > *Cc:* mapserver-users@lists.osgeo.org > *Subject:* Re: [mapserver-users] Feature select performance > > > > Steve > > The selection of layer data is done by a bounding box, though querying by > parameter values is just as slow. The mapfile is directly calling up the > shapefile (I had just followed the P.Mapper examples of displaying/querying > shapefiles directly). So probably the answers to those questions lie under > the hood of P.Mapper, which I assume is using the PHP mapscript.dll to do > the work. Is the direct query to shapefile approach v.efficient for larger > datasets..?. Ignoring the app I am using what is a good approach to large > feature datasets from a MapServer perspective? > > Thanks > Chris > > > On 24 August 2010 14:27, Lime, Steve D (DNR) <steve.l...@state.mn.us> > wrote: > > How is the selection done? How is the highlighting done? Those processes > will really impact performance depending on how things are implemented. > > Steve > > ________________________________________ > From: mapserver-users-boun...@lists.osgeo.org [ > mapserver-users-boun...@lists.osgeo.org] On Behalf Of Chris Jackson [ > webturt...@gmail.com] > Sent: Tuesday, August 24, 2010 3:19 AM > To: mapserver-users@lists.osgeo.org > Subject: [mapserver-users] Feature select performance > > > Hi all > > I have rigged up a webGIS app (P.Mapper framework) where one of the > underlying datasets is a model grid (many thousand cells) in a shapefile. > The data displays nice and quick when just viewing, but if I allow the user > to select say 5000 cells it is very (extremely) slow to redraw with the > highlighted cells. Doing the same task in a very old ArcGIS server web app > was much quicker (admittedly the data was in SDE/MS SQL). So my question is > what is the best way to improve performance - would just transferring the > shapefile to to say a MS SQL 2005 db with the MSSQLSPATIAL add-on be a good > step or is there are better way to present the data in the Map file? > Many thanks > Chris > > >
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