Re: enforcing a plan (in brief)

Although this is all true, consider that adding hints will mean that the
Pg developers *never* get bug reports to drive the optimizer improvement
process. This will have the effect of stagnating its development. I
think this would be a bad thing :-)

As an aside note that DB2 UDB does not let you hint its optimizer
either...I have heard it argued (by a IBM acquaintance of mine) that
their optimizer is better than that other database's whose name begins
with O, precisely because of this (He is biased of coarse, but it is an
interesting point).

regards

Mark

pgsql(at)mohawksoft(dot)com wrote:
> One consistent problem is the planner not being able to handle this or
> that scenario. At this stage, the *best* way to improve the planner is to
> add the ability to place hints in the plan. It *is* good enough for 90% of
> the types of queries you would ever want to do. I am dubious that you can
> get it demonstrably better in the last 10% or so without making it worse.
>
> Simple hints would go a HUGE way to improving the last 10%. Many of the
> "Why doesn't PostgreSQL use my index" questions would go away. Most of the
> time Tom spends looking at people's pg_stats info would drop. It would
> actually save time.
>
> As a PostgreSQL user, I can tell you with 100% confidence, if I had this
> tool, I could do my job easier. I can also tell you that while I have
> genuine appreciation for the current quality of the planner, I still would
> like to be able to tailor queries specifically to test various approaches
> for performance reasons.