[mapserver-users] Feature select performance

[Lime, Steve D (DNR)]

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:webturtles at gmail.com]
Sent: Tuesday, August 24, 2010 10:34 AM
To: Lime, Steve D (DNR)
Cc: mapserver-users at 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.Lime at state.mn.us<mailto:Steve.Lime at 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-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org> [mapserver-users-bounces at lists.osgeo.org<mailto:mapserver-users-bounces at lists.osgeo.org>] On Behalf Of Chris Jackson [webturtles at gmail.com<mailto:webturtles at gmail.com>]
Sent: Tuesday, August 24, 2010 3:19 AM
To: mapserver-users at lists.osgeo.org<mailto:mapserver-users at 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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