I don't know the paper you are talking about but the author of this one (David Spivak) does a ton of research on Polynomial Functors and he has a whole book on

I don't know the paper you are talking about but the author of this one (David Spivak) does a ton of research on Polynomial Functors and he has a whole book on them: https://topos.site/poly-book.pdf https://topos.site/poly-book.pdf Poly is an incredibly rich category which can be used to describe a ton of stuff such as finite state machines, neural networks, game interactions, wiring diagrams and dynamical systems more generally. I wouldn't be surprised at all if Poly can describe database migrations.