I wrote:
> ... I still see the problematic GRANT taking ~250ms, compared
> to 5ms in v15. roles_is_member_of is clearly on the hook for that.
Ah: looks like that is mainly the fault of the list_append_unique_oid
calls in roles_is_member_of. That's also an O(N^2) cost of course,
though with a much smaller constant factor.
I don't think we have any really cheap way to de-duplicate the role
OIDs, especially seeing that it has to be done on-the-fly within the
collection loop, and the order of roles_list is at least potentially
interesting. Not sure how to make further progress without a lot of
work.
regards, tom lane
