[mapserver-dev] Call for discussion on MS RFC 114: Faster retrieval of shape count

[Rahkonen Jukka (MML)]

Even Rouault wrote:
> 
> Le mercredi 10 février 2016 14:10:56, Rahkonen Jukka (MML) a écrit :
> > Even Rouault wrote:
> > > But I agree with you that the text of the standard could make think 
> > > that the server side limit should be taken into account by 
> > > resultType=hits, although it is not explicit at all...
> > 
> > What is most standard in all WFS standard versions is that they are 
> > not explicit.
> 
> Agreed...
> 
> > 
> > For me it is OK to ignore server side maxFeatures limit with 
> > resultType=hits through the metadata configuration option. At least we 
> > have considered the case.
> 
> Yes the metadata config option lets the possibility for the administrator to select the desired behaviour.

The drawback is that users can't know what the administrator has decided to do and one service sends different results than some other.
I think that there would be an obvious benefit if WFS had support for both query types. I am pretty sure that every SQL user does sometimes
a) select count(*) from table;
but also
b) select count(*) from table where attribute=...;

 
> I'm now wondering if defaulting wfs_ignore_server_maxfeatures_for_hits to true is appropriate in the PostGIS case. Before you pointed out that issue, I thought initially that ignoring the server maxfeatures limit for hits was the compliant way, but it is not so clear. On the other side, even if we are not compliant with the RFC implemented, we'll behave the same as other WFS server implementations... 

I fear it is rather "behave the same as SOME other WFS server implementations..." . At least deegree is sending the same count than resultType=results from http://demo.deegree.org/utah-workspace/

I tested by selecting the wfs service URL and changing BBOX in request:
<GetFeature xmlns="http://www.opengis.net/wfs" xmlns:app="http://www.deegree.org/app" xmlns:gml="http://www.opengis.net/gml" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.1.0" xsi:schemaLocation="http://www.opengis.net/wfs http://schemas.opengis.net/wfs/1.1.0/wfs.xsd"
resultType="hits">
  
  <Query typeName="app:DominantVegetation">
  
  <PropertyName>app:objectid</PropertyName>
  <PropertyName>app:code</PropertyName>
  
  <ogc:Filter>
    <ogc:BBOX>
      <ogc:PropertyName>app:geom</ogc:PropertyName>
      <gml:Envelope srsName="urn:ogc:def:crs:EPSG::26912">
        <gml:lowerCorner>414055.0 4404348.0</gml:lowerCorner>
        <gml:upperCorner>452132.0 4426933.0</gml:upperCorner>
      </gml:Envelope>
    </ogc:BBOX>
  </ogc:Filter>
  
  </Query>
</GetFeature>

I found one ArcGIS server and that does not support resultType at all:

http://gtkdata.gtk.fi/arcgis/services/GTKWFS/MapServer/WFSServer?service=wfs&version=1.1.0&request=getfeature&typename=GTKWFS:kallioperahavainnot&resultType=hits&maxfeatures=1

-Jukka-