[wongarsu]

By that same reasoning Postgres is it's own micro service. It runs as a separate process, you communicate with it over a well defined API, and it's subcomponents (data store, query optimizer etc) are encapsulated.

With enough framing everything is possible, and in some contexts it will even make sense.

[mumblemumble]

It has to do with how it functions in practice, IMO. PostgreSQL itself is arguably a service, but the database probably is not - you're probably crawling all over its implementation details and data model.

You could take a stand and say, "All access is through stored procedures. They are the API." And, if that API operates as the same semantic level as a well-crafted REST API, then you could make an argument that that particular database is a microservice that just happens to have been implemented on top of PostgreSQL. But I don't think I've ever seen such a thing happen in the wild. It's much more popular to use an ORM to get things nice and tightly coupled.

[selfhoster11]

Such implementations exist and have been discussed a few days ago here on HN. There are also REST adapters for Postgres: https://github.com/PostgREST/postgrest