Re: Proposed patch to make mergejoin cost estimation more symmetric

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