If I'm just doing DB schema documentation, and I don't need to integrate that documentation into broader technical documentation, schemaspy is the tool I reach for.

http://schemaspy.org/

My impression is that the maintainers are Oracle-centric (I don't interact with the project with any regularity, so this could be mistaken), but I use this with PostgreSQL and have been quite pleased.

Similar tool with awesome interface & bridges would be dbdiagram.io [0]. Not affiliated, just a happy user.

Imports from MySQL, PostgreSQL, SQL Server, works with Rails, Django etc.

[0]:https://dbdiagram.io/

Is there some tool to go the other way? I actually design my schemas before creating them. It would be nice to start with a high level ERD in PlantUML, add it to a larger design doc, review with the team and refine and then push a button to get my DDL.

Will give this a try! With all the UML discussions lately it's made me nostalgic for having an ER diagram of my schema. This even looks simple / dependency free enough to run in a CI tool to keep such a diagram up to date with the codebase.

We use planter in our build process to maintain an up-to-date visualization of the schema. Given that foreign key references are maintained in the schema (using REFERENCES), planter draws all relationships properly.

The Plant UML CLI itself has some limitations if the ER diagram is really large.