Re: pg_trigger.tgparentid

Thanks both -- pushed.  I also changed regress/sql/triggers to leave
tables around that have a non-zero tgparentid.  This ensures that the
pg_upgrade test sees such objects, as well as findoidjoins.

I refrained from doing the findoidjoins dance itself, though; I got a
large number of false positives that I think are caused by some pg12-era
hacking.

-- 
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services