Hi Lukas, I'm back from vacation and did some measurements this morning. I also find that #3 performs better than #4 with a more complicated query. In this experiment, #3 needs more buffer reads than #4 (#4 uses 20% less buffer reads), but performs much better (#4 needs 60% more time than #3).
So unless an oracle guru advises against it, I would implement #3. cu. stan.
