hstore

You already could do that with postgres hstore, I think, but postgres hstore is limited to a flat list of key/values, not nested data structures like json.

Due to its restrictions, an hstore can also be converted to and from a record type (think database row).

But Postgres ships with hstore and json store for people who want to go schema-less.

It's also easier to manipulate hstore values then json values within the database.

Likewise, Django has had third-party hstore and jsonb fields for ages, but I take your point.

Specifically no not miss getting acquainted with json and hstore, specifically using json as a variable size argument passing and returning mechanism, it's just hilariously effective.

This is something I've often talked about, hstore is a key value store.

I've been wishing for a while though that Rails ActiveRecord would support the atomic partial update operations inside hstore that postgres already does.

As someone who had to do aggregation on hstore...

I just created a couple of indexes on our DML audit logging archive table this afternoon, which stores old and new row state in hstore fields.

However hstore has been a part of Postgres since version 8.2 released in 2006, and I think was around as a third-party project before that, so it's used by a lot of projects.

I don't like using array and hstore if I know I will need to aggregation on them later, but sometimes you get stuck with a design that has them, or you end up having to run calculations you never thought you would.

Regarding having a last, nullable "data" hstore or jsonb column, I think it's a very good practice.