Re: Joins on TID

What I'm thinking about in this thread is joins on TID, which we have only
very weak support for today --- you'll basically always wind up with a
mergejoin, which requires full-table scan and sort of its inputs.  Still,
that's better than a naive nestloop, and for years we've been figuring
that that was good enough.  Several people in the other thread that
I cited felt that that isn't good enough.  But if we think it's worth
taking seriously, then IMO we need to add both parameterized scans (for
nestloop-with-inner-fetch-by-tid) and hash join, because each of those
can dominate depending on how many tuples you're joining.