Re: query optimizer

On Tuesday 17 April 2007 Tom Lane's cat, walking on the keyboard, wrote:
> "jungmin shin" <jungmin(dot)shin(at)gmail(dot)com> writes:
> > As I see the documentation of postgres, postgres use genetic algorithm
> > for query optimization rather than system R optimizer. right?
>
> Only for queries with more than geqo_threshold relations. The join
> search algorithm for smaller queries is a System-R-like dynamic
> programming method.
>

Hi,
I'd like to better understand how the optimizer works and is implemented. Is
there any available documentation (before start reading the source!) to
understand concepts about geqo and system r? Any chance about any demo or
presentation with detailed examples (about how the optimizer makes and
discards choices, not about how to read the planner output)?

Thanks,
Luca