I agree. If we are to support UPDATE .. ORDER BY .. LIMIT, it should work with inheritance. So the path forward is (using Marko's phrasing upthread):
1) We put the LIMIT inside ModifyTable like this patch does. This doesn't prevent us from doing ORDER BY in the future, but helps numerous people who today have to 2) Someone rewrites how UPDATE works based on Tom's suggestion here: http://www.postgresql.org/message-id/1598.1399826841@sss.pgh.pa.us, which allows us to support ORDER BY on all tables (or perhaps maybe not FDWs, I don't know how those work). The LIMIT functionality in this patch is unaffected.
What's not clear to me is whether it make sense to do 1) without 2) ? Is UPDATE .. LIMIT without support for an ORDER BY useful enough?
I've wanted LIMIT even without ORDER BY many times, so I'd vote yes.
And if we apply this patch now, how much of it needs to be rewritten after 2) ? If the answers are "yes" and "not much", then we should review this patch now, and put 2) on the TODO list. Otherwise 2) should do done first.
