I'm also wondering about primary keys. We have a table without a primary key, because the only way to uniquely identify a row is with all attributes at once. GD does not let me create a table with no primary key, so I tried creating an "All" primary key that includes all attributes, but then I get an error

Datasets contain primary key or references consisting of 2+ entities

. Found a mention of this in the documentation, I didn't want to add an arbitrary primary key since this is the largest table we will have, but I will do that if there's no other way.

Hi Daniel, the limitation is as you mention. We are considering lifting this in the future releases, though.