It's ugly but having a field that's just a dictionary is really handy and not too ugly. We use a lot of them for things like "tags" (which can take freeform us

It's ugly but having a field that's just a dictionary is really handy and not too ugly. We use a lot of them for things like "tags" (which can take freeform user- or ml- supplied image tags in key:value format). I adore it. (We tried mongo with one of our annotation systems and regretted it.) It's a very nice way to balance quick development (you don't need a schema change to try a feature for a while) with the benefits of a mostly schema-defined db.