Re: Damage control for planner's get_actual_variable_endpoint() runaway

On Mon, Nov 21, 2022 at 10:32 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > Is there any reason to tie this into page costs? I'd be more inclined
> > to just make it a hard limit on the number of pages. I think that
> > would be more predictable and less prone to surprising (bad) behavior.
>
> Agreed, a simple limit of N pages fetched seems appropriate.
>
> > And to be honest I would be inclined to make it quite a small number.
> > Perhaps 5 or 10. Is there a good argument for going any higher?
>
> Sure: people are not complaining until it gets into the thousands.
> And you have to remember that the entire mechanism exists only
> because of user complaints about inaccurate estimates.  We shouldn't
> be too eager to resurrect that problem.
>
> I'd be happy with a limit of 100 pages.

OK.

-- 
Robert Haas
EDB: http://www.enterprisedb.com