What I'd like to understand about this patch is how it relates to Amit L.'s work on making the planner faster for partitioned UPDATE/DELETE cases (https://commitfest.postgresql.org/22/1778/). I think that that might render this moot? And if it doesn't, how much does it really matter? You can't really postpone taking a lock on a relation that the planner is going to do anything nontrivial with.
regards, tom lane
