I was wondering how far away OrioleDB was from becoming a pure extension instead of being a postgres fork. I'm not an expert by any means on TAM - but was curious if the Orioledb team managed to upstream some parts of their fork.

imho: not soon.

Most alternative PG storage engines have stumbled, and OrioleDB touches a lot of core surfaces. The sensible order is: first make OrioleDB rock-solid and bug-free; ( https://github.com/orioledb/orioledb/issues?q=is%3Aissue%20s... ) then, using real-world feedback and perf data, refactor and carve out patches that are upstream-ready. That’s a big lift for both the OrioleDB team and core PG.

From what I understand, they’re aiming for a release candidate in the next ~6 months; meaningful upstreaming would come after that.

In other words: make it work --> validate the plan --> upstream the final patches.