Parallell Optimizer

I asked a while ago in this group about the possibility to implement a
parallel planner in a multithread way, and the replies were that the
proposed approach couldn't be implemented, because the postgres is not
thread-safe. With the new feature Background Worker Processes, such
implementation would be possible? If yes, do you can see possible problems
in implement this approach, for example, the bgprocess can't access some
planning core functions like make_join_rel, acess them in parallel and so
on. I want start a research to work in a parallel planner in postgres, I
succeeded in in the DBMS H2, but my first option still is the postgres, and
any help is welcome.

Att,

Fred