Re: Proposed patch to make mergejoin cost estimation more symmetric

Tom Lane wrote:
> 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).

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.

--
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
Criptografía: Poderosa técnica algorítmica de codificación que es
empleada en la creación de manuales de computadores.