Re: patch for geqo tweaks

Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> writes:
> Tom Lane wrote:
>> Having said that, though, I believe that it's also probably a
>> *different* initial shuffle, which may well mean that GEQO gives
>> different plans in some cases. That doesn't bother me as long as
>> we only make the change in HEAD, but does anyone want to complain?

> Uh, do we promise that plans found by geqo are stable? That would seem
> odd to me -- wouldn't they change shape on a whim, say because the stats
> are different? It seems odd to look for plan stability using a genetic
> algorithm.

Well, obviously any plan might change if the stats change. But we do
promise repeatable plans given identical input data, cf commit f5bc74192.

regards, tom lane