[Daynil]

I often read things that say that if you just write the query properly, you can trust the query optimizer to select the right plan. Just trust the optimizer! Unfortunately, in my experience, the more complex your query gets, the more opportunities the optimizer has to get it terribly wrong. I've learned to accept that, if the "clear/clean" version of the SQL (that the human likes to read and write) does not produce acceptable results, you just have to drop more explicit hints to the optimizer about what you want it to do. Query optimizers are truly awesome pieces of software, you just have to learn to work around their limitations when you hit them.