On Thu, Mar 15, 2018 at 11:01 AM, Tom Lane <t...@sss.pgh.pa.us> wrote: > It might be worth looking at whether we couldn't fix the single-member- > Append issue the same way we fix no-op SubqueryScans, ie let setrefs.c > get rid of them. That's not the most beautiful solution perhaps, but > it'd be very localized and low-risk.
That's definitely a thought; it's a probably the simplest way of saving the run-time cost of the Append node. However, I don't think it's a great solution overall because it doesn't get us the other advantages that David mentions in his original post. I think that to gain those advantages we'll need to know at path-creation time that there won't ultimately be an Append node in the finished plan. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
