Metabase is GORGEOUS, by far the best BI system – and we have tested a lot of them.
We are using it, among other things, to check on the advancement of our work. An important part of it is how complete our database is getting.
So, basically, each column in the database can have information input in it or be NULL.
I have not found a way to draw a pie chart showing the ‘input/not input’ division, except by creating a boolean column and filling it in the database, which is awkward.