Training a 4B model to produce 81% faster query plans than Postgres

Leis et al. asked this exact question in 2015. Then, they asked it again 10 years later .

Despite an enormous body of research spanning a decade since their original exploration, they found that query optimizers continue to leave much to be desired.

I was surprised when I first learned about this. A Postgres database should know everything about the stuff that lives in its tables, no? How hard can it be?

As it turns out: enormously hard. In fact, one particular task a query optimizer needs to do, join ordering, is known to be NP-hard .