I am trying to create a polygon shapefile layer in QGIS (2.12.1). Because I will be creating many polygons I'm not going to be able to maintain a unique id number manually (without keeping track of it on a piece of paper or something, which is exactly the sort of thing these fancy computers were supposed to replace).
I'm trying to follow these instructions to automatically assign an id after the fact, but every attempt I make to edit the "id" column fails to persist. As soon as I save the edits (or just try sorting the attribute table on the id column or something) everything reverts to
I see the same behavior in 2.12.0 as well.
Is this supposed to work? Am I missing something obvious?