json isn't necessarily columnar, but it is a natrual fit for stuff that is columnar that's otherwise harder to model in a traditional relational db

here's my usecase:

- we have a bunch of attributes (all different names by customer, and many different values for each record that a customer stores)

- it's a fairly natural fit for a json value with only one level of key: value mapping

- we use mysql on GCP (no columnar plugins, too hard to switch to postgres)

Someone could go back in time and correctly model it as columns and not json but that ship has sorta sailed. While it's not impossible to change, it would be pretty hard, time will tell if that ends up happening.

I would love to be able to tell mysql "put this column in a collumnar engine and use that when I query on it" (AlloyDB is this for postgres on GCP)