I am working on ownership data at a US county level. I have one shapefile per county that contains thousands of tax parcels. I need to dissolve the polygons representing parcels owned by the same individual. When the shapefile is not clean, the "Dissolve" tool in QGIS doesn't seem to work, it freezes. I have to fix the geometry validity issues first using the "Check Geometry Validity" tool. However, I have sometimes hundreds of errors. It takes a lot of time to fix them manually. Is there any other strategies that could save me some time?
I am using QGIS 2.4.0.