On Sun, Sep 20, 2009 at 8:52 AM, Pavel Iacovlev <[email protected]> wrote: > 1) > I would start investigating from MapServer. What are your layer values for > TOLERANCEUNITS pixels > TOLERANCE 10 (your value here)
Thanks, will look at that setting. Right now I don't have any tolerance values set. > > 2) > Do you debug your requests with firebug ? Yes. The interesting thing is... protection should be n-ways... OpenLayers should allow setting min/max values of bbox queries (perhaps it does; haven't explored that yet), MapServer should not send queries that cause a hang (but, how is it to know?), and, most importantly, Pg shouldn't hang when the bbox is smaller than the geometry. In this, my geometry is 1 km by 1 km, and the bbox being sent is smaller. Also, instead of finding all the geometries that fall within a bbox, the correct result really should be the geometry within which my click falls. > > Your speed should not be constant, you should get faster responses for > smaller bboxes. > > On Sun, Sep 20, 2009 at 4:28 PM, P Kishor <[email protected]> wrote: >> On Sun, Sep 20, 2009 at 2:47 AM, Pavel Iacovlev >> <[email protected]> wrote: >>> You can enable debug of Mapserver >>> http://mapserver.org/development/rfc/ms-rfc-28 >>> >>> You can configure PostgreSQL to log all your queries. Here is a tool >>> to analyze them and how to make PostgreSQL log them >>> http://pgfouine.projects.postgresql.org/tutorial.html >>> >>> Mapserver computes the current bbox view and sends the query to >>> PostGIS and then you get all the geometries that are inside that bbox. >>> Thats why you should create a GisT index to speed things up. >>> >> >> Thanks for the logging info. I will do so. Actually, I do have a Gist >> index on my layer. It is a simple, lat/lon grid over my study area. I >> have a WMSGetFeatureInfo control in OpenLayers that returns the xmin, >> ymin, xmax, ymax for the grid square containing the user's mouse >> click. >> >> When I am zoomed out (example queries below), the bbox is >> >> xmax: -88.026581 ymax: 45.970243 >> xmin: -89.435577 ymin: 45.325117 >> >> The result comes back immediately. >> >> When I am zoomed in, the result never comes back. The bbox sent in the query >> is >> >> xmax: -88.643017 ymax: 45.688914 >> xmin: -88.819141 ymin: 45.608274 >> >> >> As you can see, the bbox in the second query is very small, and my >> guess is, no geometry is found within that bbox. That itself is >> erroneous, however, the funny thing is, I don't even get a "0" result. >> There is simply no response from the server, and my user interface >> just hangs, waiting for a response to WMSGetFeatureInfo. >> >> From the user's perspective, this is confusing. Since I am requesting >> the info for the grid square in which my click is contained, its speed >> should be constant, no matter how much I am zoomed in or out. After >> all, the mouse can have only one click x,y, and that click can only be >> contained within one grid square, no matter what my zoom level. Of >> course, when I am zoomed out, then the precision of which grid square >> my click falls within is very coarse, and I may not get the correct >> grid square back, however, when I am zoomed in, I should be able to >> more accurately click within the grid square I desire. So, actually, >> zooming in is, from the user's perspective, a desired state. >> >> I am not sure which technology here is at fault. I have OpenLayers, >> MapServer and PostGIS in play, and something is failing to work as >> intuited. >> >> Any suggestions? >> >> >> >> >>> On Sun, Sep 20, 2009 at 7:15 AM, P Kishor <[email protected]> wrote: >>>> I am trying to understand the mechanics of a getfeatureinfo query. My >>>> setup is data in Pg/PostGIS, served by MapServer via WMS, with >>>> OpenLayers in the front. When I click on a map and send a >>>> GetFeatureInfo query, MapServer grabs the x,y sent in the URL, and, >>>> for the layer (also sent in the URL), finds the row in the table which >>>> contains the x,y of my click. >>>> >>>> How does MapServer do that? >>>> >>>> Does it run a Pg/PostGIS query for this? >>>> How can I find out the syntax of this query? >>>> >>>> If a GetFeatureInfo takes too long, what can I do to speed it up? >>>> >>>> >>>> -- >>>> Puneet Kishor >>>> _______________________________________________ >>>> postgis-users mailing list >>>> [email protected] >>>> http://postgis.refractions.net/mailman/listinfo/postgis-users >>>> >>> >>> >>> >>> -- >>> http://iap.md, The future is open >>> >> >> >> >> -- >> Puneet Kishor http://www.punkish.org >> Carbon Model http://carbonmodel.org >> Charter Member, Open Source Geospatial Foundation http://www.osgeo.org >> Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor >> Nelson Institute, UW-Madison http://www.nelson.wisc.edu >> ----------------------------------------------------------------------- >> Assertions are politics; backing up assertions with evidence is science >> ======================================================================= >> Sent from Madison, WI, United States >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > > > > -- > http://iap.md, The future is open > -- Puneet Kishor http://www.punkish.org Carbon Model http://carbonmodel.org Charter Member, Open Source Geospatial Foundation http://www.osgeo.org Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor Nelson Institute, UW-Madison http://www.nelson.wisc.edu ----------------------------------------------------------------------- Assertions are politics; backing up assertions with evidence is science ======================================================================= Sent from Madison, WI, United States _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
