I have a couple of tables (three) with polygons (landuse coverage in this case). Within each table, there is no overlap, but between tables there might be a lot of overlap.
I would like to combine the polygons from the tables into a single table with polygons with no overlap. To resolve situations where the source tables overlap, I would like to put a priority on each layer, so that polygons from the layer with highest priority is used for the overlap.
One way to visualize what I want to do is drawing the tables on top of each other, discarding already drawn polygons where there is overlap. You could also say I want to merge the three tables into one. (Please inform me if there is some more appropriate terminology to describe what I want to do.)
A big issue in this case is performance: each of the tables contain millions of polygons.