Postgres Is. Introducing PostgreSQL compatibility index

I appreciate the idea of this a lot but am a bit skeptical.

The good thing is this would at least shine a better light on all those that "claim" to be Postgres but really have little to nothing to do with it. Overwhelmingly people are supporting the wire protocol despite being a completely separate database because Postgres is already so universal and it'd be a huge investment to recreate that ecosystem of language drivers and everything else around it.

The reality is even "wire protocol" there are varying levels of support depending on what you're trying to do.

Then when you get down to functionality, it could be "we support the Postgres data types"... well except this one or that one. That's fine and good until a user is surprised 2 years into building an application.

Even the notion of we support all Postgres extensions, well all Postgres extensions don't work together some take hooks and change queries that other extensions want to modify for themselves.

Having worked with Postgres and managed Postgres for a very long time. Postgres is Postgres, there are extensions that modify Postgres, there are forked versions of Postgres, and things that are "Postgres" compatible simply aren't Postgres.