On Fri, May 29, 2015 at 12:59 AM, Merlin Moncure <mmoncure@gmail.com> wrote:
On Wed, May 27, 2015 at 3:06 PM, boix <boix@uclv.cu> wrote: > Hello, my partner and me are working with the goal of improve the GEQO's > performance, we tried with Ant Colony Optimization, but it does not improve, > actually we are trying with a new variant of Genetic Algorithm, specifically > Micro-GA. This algorithm finds a better solution than GEQO in less time, > however the total query execution time is higher. The fitness is calculated > by geqo_eval function. Does anybody know why this happens? > > We attach the patch made with the changes in postgresql-9.2.0.
can you submit more details? for example 'explain analyze' (perhaps here: http://explain.depesz.com/) of the plans generated GEQO vs GA vs stock? It sounds like you might be facing an estimation miss which is not really an issue a better planner could solve.
That said, assuming you're getting 'better' plans in less time suggest you might be on to something. merlin
What sort of tests are you running? I suspect that anything which is not too well thought out and tested might end up performing well only on small subset of tests.
Also, what is the consistency of the plans generated? If you are only targeting planning time, I feel it might be of lesser value. However, if you can get large order joins to be executed in a near optimal (brute force) solution, you might be on to something.
Something I would like to see done is remove the dead code that is present in existing GEQO. This might alone lead to lesser compilation times.