1) I would start investigating from MapServer. What are your layer values for TOLERANCEUNITS pixels TOLERANCE 10 (your value here)
2) Do you debug your requests with firebug ? 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 _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
