On Wed, Mar 23, 2011 at 6:00 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Claudio Freire <klaussfreire(at)gmail(dot)com> writes:
>> In my head, safer = better worst-case performance.
>
> If the planner starts operating on the basis of worst case rather than
> expected-case performance, the complaints will be far more numerous than
> they are today.
I imagine, that's why, if you put my comment in context, I was talking
about picking a safer plan only when the "better on average one" fails
miserably.