I am currently working on a set of data that defines restricted areas for use of photovoltaic modules.
This set of data amounts to 270.00 polygons in total [with their own geometry].
For simpler application in the future, I now want to dissolve the Layer to have just one polygon instead of almost 300.000. After running the dissolve function for an incredible 28h, it finally created an output layer. However, this layer can not be shown visually in QGIS, or used for further processes (even though it shows a data set of one polygon within the attribute table).
I already ran a geometry check on the layer which stated that the geometry of the input layer [undissolved layer] is flawed. I then buffered the layer by 0, and tried the geometry repairing extension to QGIS. Both could not solve the problem, and took tremendous time to do.
I also tried to cut the big layer in data sets of 20.000 and dissolve these layers, before putting them together in a layer again before dissolving this layer. This however, also didn't work and cost me a total of 2 weeks working on it.
Now I am wondering why the undissolved layer can be displayed by the program without any problem, but no algorithm [like dissolving] can be run on the layer.
Note that any of the algorithms can be run for the individual polygons within the layer, if run on one single polygon at a time [tested for 500 individual polygons out of the 270.000 total polygons]
How can I either repair the multipolygon player without swallowing all my computing power for another week, or effectively find the flawed polygons within the layer to repair them individually?
Is there an approach to simplify a layer that big without taking literal days?.