"Mark Woodward" <pgsql@mohawksoft.com> writes:
> I would say that a "simpler" planner with better hints
> will always be capable of creating a better query plan.
This is demonstrably false: all you need is an out-of-date hint, and
you can have a worse plan.
The argument against hints is not about whether someone could knock
together a crappy hint facility and be able to get some use out of it.
It is about how much work it would take to design a *good* hint facility
that makes it easy to maintain hints that are robust in the face of data
and query changes. If someone were to sit down and design and build
such a thing, it'd very likely get accepted into core Postgres --- but
personally, I think the equivalent amount of effort would be better
spent on improving the planner and the statistics.
As Josh already noted, Oracle-like hints are pretty likely to get
rejected ... not only because of doubts about their true usefulness,
but out of fear of falling foul of some Oracle patent or other.
regards, tom lane