Rendering a large MSSQL-Layer in QGIS 2.18 is very slow. The same segment takes in 2.14.1 about 10 seconds and in 2.18.3 about 2 minutes. In 2.16.1 or 2.18.1 it is also very slow.
What can be the reason for this?
My MSSQL-Layer has about 3,1 millions polygon-objects. I found out that the rendering-process is different in the two QGIS-Versions (2.14 and 2.18):
- The drawing of the objects in full extent in QGIS 2.14 is scattered (not grouped together!). The objects come into sight scattered over the full extent of the map. Here is an image from the first seconds of rendering:
If I scale then to a detail section, rendering is very fast.
- Otherwise the drawing of the objects in full extent in QGIS 2.18 is grouped. The objects come into sight grouped in regions. Here is an image from the first seconds of rendering:
If I scale then to a detail section, rendering is very slow.
Is there a way to render the layer in 2.18 like in 2.14? Why is there a difference in the render process?
Was there a known general change in the render process in QGIS or could it be a wrong adjustment of my QGIS Installation?
EDIT in Sept. 2017:
I have tested the rendering performances described above with QGIS 2.99.0 (I think Version 36). But the problem is still the same as in 2.18.
Is there a possibility to speed up rendering in 3.0?