[QGIS-Developer] Rendering layers from MSSQL Server fail

[Pedro Venâncio]

Hi all,

I don't have too much experience in MSSQL Server, but I've created some
views that get some points (GPS positions) and convert them to lines.

Everything works fine, MSSQL Server shows the geometries correctly.

When I load them in QGIS, some of the lines simply don't show up on canvas,
but they are listed in the attribute table.

If I convert the binary geometry column to WKT, and put the WKT of the
geometries that does not render in QuickWKT plugin, they are rendered fine.

If I select, in the attribute table, the records that does not render and
run Extract Selected Features, they export fine and all geometries show up
as expected.

I also have run the Check Validity and here is the interesting thing:

 1) Using the GEOS method, all geometries are classified as valid and all
of them render as expected. Invalid and error output layers are empty.

 2) Using the QGIS method, all geometries are classified as invalid and
stay in the Invalid output layer. However, they are all rendered! The
errors are of two types: 'segments 47 and 69 of line 0 intersect at
-7.27335, 40.5264' and 'line 1 contains 2 duplicate nodes starting at
vertex 13'.

So, those errors does not seem to be a reason to not render the geometries,
since they are rendered in another formats.

Any hint about what can be happening?

Thank you very much!

Best regards,
Pedro Venâncio
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