[QGIS-Developer] QGIS WMS provider firing too many requests !?

[Jeff McKenna]

Hi Richard,

Yes I've noticed this also, I just never spent time to examine why.  For 
example, using my own WMS service I zoomed in and QGIS fired 11 GetMap 
requests to my server.  It's difficult to trigger though (I can't 
reproduce with your NL service).  Bizarre.  But I have definitely seen 
9+ GetMap requests for the same service/layer.

-jeff






-- 
Jeff McKenna
GatewayGeo: MapServer Consulting and Training Services
co-founder of FOSS4G
http://gatewaygeo.com/





On 2021-02-13 11:29 a.m., Richard Duivenvoorde wrote:
> Hi,
> 
> As a vivid WMS user/debugger, I see that QGIS is firing 9 requests per 'view-extent' currently.
> 
> I'm aware of cache etc etc... but... especially when using temporal filters for example, do others agree with me that this is more or less useless?
> I'm also aware that a lot of WMS are actually just WMS interfaces in front of a cached WMTS, but still.
> 
> - some (governmental) services nowadays are still free for fair use, but: firing 9 times the actual requests costs resources/energy/maybe money
> - before the WMTS I ran WMS services sometimes with pretty heavy styling, so on higher zoomlevels you do NOT want your clients to fire 9 requests, and just effectively use 1 ...
> 
> So in short: should I try to add some kind of (hidden?) option to minimize the number of requests?
> 
> To test a wms of all municipalities of NL:
> 
> https://geodata.nationaalgeoregister.nl/bestuurlijkegrenzen/ows?SERVICE=WMS
> (layer 'gemeenten', EPSG:28992)
> And look in F12/debugging window the number of GetMap requests fired when zoomed in...
> 
> I copied/created polgyons of the requests, and (see screenie) indeed looking at the center 'tile', the 8 surrounding requests are also fired....
> 
> Currently looking into this.
> 
> Regards,
> 
> Richard Duivenvoorde
> 
> 
>   
>