Tomas Vondra <tomas@vondra.me> writes:
> I wonder if it's time to consider updating the random_page_cost default
> value. There are multiple reasons to maybe do that.
Re-reading the old links you provided, I was reminded that the 4.0
value came in with some fairly fundamental changes to the cost model,
such as accounting for WHERE-clause evaluation explicitly instead of
assuming that it was down in the noise. I can't help wondering if
it's time for another rethink of what the cost model is, rather than
just messing with its coefficients. I don't have any concrete ideas
about what that should look like, though.
Another angle is that I expect that the ongoing AIO work will largely
destroy the existing model altogether, at least if you think in terms
of the model as trying to predict query execution time. But if what
we're trying to model is net resource demands, with an eye to
minimizing the total system load not execution time of any one query,
maybe we can continue to work with something close to what we've
traditionally done.
No answers here, just more questions ...
regards, tom lane
