Simon Riggs <simon@2ndquadrant.com> writes: > I do have a longer term issue that there is no information provided by > EXPLAIN to allow us to differentiate these two conditions. Sure there is: the new startup condition affects the estimated plan startup cost (only) and the existing termination condition affects the estimated total cost (only). regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings

Gregory Stark <stark@enterprisedb.com> writes: > What about a merge join against an empty table? I suppose there would just be > no statistics? Yeah. The defenses against silly results in mergejoinscansel should be enough to prevent it from doing anything really insane. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 7: You can help support the PostgreSQL project by donating at http://www.postgresql.org/about/donate

Alvaro Herrera <alvherre@alvh.no-ip.org> writes: > Yes, but how can you tell by looking at the explain? I think the point > is that the "fraction that would be skipped" should be reported somehow. It is: it's directly reflected in the startup cost. Previously, a mergejoin would always have startup cost equal to the sum of its input startup costs (hence, zero in the cases of interest here). regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to majordomo@postgresql.org so that your message can get through to the mailing list cleanly