I'm Grzegorz Parka, BSc Engineer of Technical Physics and student of Computer Science at WUT, Poland. Last year I've been a bit into evolutionary algorithms and during my research I found out about GEQO in Postgres. I also found out that there are plans to try a different attempt to find optimal query plans and thought it could be a good thing to use it as a project for GSoC.
I'm interested in one of old TODO items related to the optimizer - 'Consider compressed annealing to search for query plans'. I believe this would be potentially beneficial to Postgres to check if such a heuristic could really choose better query plans than GEQO does. Judging by the results that simulated annealing gives on the travelling salesman problem, it looks like a simpler and potentially more effective way of combinatorial optimization.
As deliverables of such a project I would provide a simple implementation of basic simulated annealing optimizer and some form of quantitative comparison with GEQO.
I see that this may be considerably bigger than most of GSoC projects, but I would like to know your opinion. Do you think that this would be beneficial enough to make a proper GSoC project? I would also like to know if you have any additional ideas about this project.