Feature request #1421

WFS Extension doesn't request displayed extent using bbox

Added by Marco Lechner almost 12 years ago. Updated over 10 years ago.

Status:Closed
Priority:Low
Assignee:Marco Hugentobler
Category:Web Services clients/WMS
Pull Request or Patch supplied: Resolution:fixed
Easy fix?:No Copied to github as #:11481

Description

Using the WFS-Extension to request vectordata from a WFS-Service doesn't request only the data of the displayed extend using bbox in requeststring. It request the whole layer! This could be pretty (too) much.

By the way "WFS" is missing in Component-list in this trac system.

History

#1 Updated by Marco Hugentobler almost 12 years ago

Hi Marco

The WFS provider fetches the whole layer the first time and stores all in memory. Because it assumes that the user soon will do some panning and zooming and that will be a lot faster if everything is in memory. So the implemented solution requires more memory but is much faster for many zoom and pan actions.

And if a WFS layer is the first one, QGIS would need to fetch the whole layer anyway.

However, it could be a feature enhancement to give the user the possibility to only request the data in the current view extent (those features then would stay the same even if the user pans or zooms out afterwards). I'm therefore changing this ticket into enhancement (and category 'data provider')

Marco

#2 Updated by Jürgen Fischer almost 12 years ago

a side effect of that behaviour also is, that the provider only shows a snapshot of the content and there is no way to update it other than removing and re-adding the layer or reloading the project.

#3 Updated by Marco Lechner almost 12 years ago

wouldn't it be better to preload some larger bbox than the viewed extend (easy to implement). I try to use a WFS serving a huge amount of data for whole europe (OpenStreetMap-WFS) - but I only need the features in a small part (surrounding of Freiburg, Germany) wich is already a lot of data.
Loading the whole layer takes about five minutes (and I used a relatively small one for testing)

#4 Updated by Marco Hugentobler over 10 years ago

  • Resolution set to fixed
  • Status changed from Open to Closed

An option to fetch only the feature intersecting the current map extent is in the svn version.

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