Re: Sub-optimal plan chosen

On Thu, Sep 10, 2009 at 9:57 AM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:

> 2009/9/10 <tv(at)fuzzy(dot)cz>:
> >> Playing around with seq_page_cost (1) and random_page_cost (1), I can
> get
> >> the correct index selected. Applying those same settings to our
> production
> >> server does not produce the optimal plan, though.
> >
> > I doubt setting seq_page_cost and random_page_cost to the same value is
> > reasonable - random access is almost always more expensive than
> sequential
> > access.
>
> If the data figures to be read from the OS cache, it's very
> reasonable, and the right value is somewhere in the 0.05 - 0.10 range.
>
>
For the most part, it will indeed be cached. Thanks for the tip on the
values.