I have a shapefile that contains many polygons(>200,000). Some of these polygons are assigned the same ID number. None of the polygons overlap other polygons. I need to find a way to select out all of the polygons that have the same ID number as another polygon for further processing.
I have looked into finding all the duplicates in an Excel sheet and then joining this to the shapefile attribute table but this would take almost as long as manually selecting each shape. I would like a way to select all these out only using QGIS.