There's a fascinating gap between PostgreSQL theory and practice here. Elsewhere in this thread, I complained that PostgreSQL extensions can't do everything yet. One thing they can do, however, or ought to be able to do, is provide alternative storage engines. That's the central thing they're supposed to be especially good at providing.

So what did the VACUUM-free, undo-based MVCC storage engine project stall? https://wiki.postgresql.org/wiki/Zheap

Why is there no InnoDB for PostgreSQL?

(Maybe OrioleDB will avoid a similar fate.)