On Sat, 22 Dec 2018 at 16:31, Tom Lane <t...@sss.pgh.pa.us> wrote:
> 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. > That would certainly help if you are building a column store, or other new index types. -- Simon Riggs http://www.2ndQuadrant.com/ <http://www.2ndquadrant.com/> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
