Re: Initial prefetch performance testing

Gregory Stark <stark(at)enterprisedb(dot)com> writes:
> Perhaps access paths which expect to be able to prefetch most of their
> accesses should use random_page_cost / effective_spindle_count for their i/o
> costs?

> But then if people don't set random_page_cost high enough they could easily
> find themselves with random fetches being costed as less expensive than
> sequential fetches. And I have a feeling it'll be a hard sell to get people to
> set random_page_cost in the double digits let alone triple digits.

Well, we could use something like
Max(random_page_cost / effective_spindle_count, seq_page_cost)
to ensure the result remains somewhat sane.

regards, tom lane