Re: Make ringbuffer threshold and ringbuffer sizes configurable?

Hi,

On 2020-02-06 13:15:04 -0500, Robert Haas wrote:
> On Wed, Feb 5, 2020 at 11:00 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > I.e. to maintain the current defaults, seqscan_ringbuffer_threshold
> > would be -4.0, but could be also be set to an absolute 4GB (converted to
> > pages). Probably would want a GUC show function that displays
> > proportional values in a nice way.
>
> I think this is kind of awkward given that our GUC system attributes
> units to everything.

I admit it's awkward. I think we possibly could still just make the size
displayed in bytes in either case, reducing that issue a *bit*?

> It'd sort of be nicer to have two separate GUCs,
> one measured as a multiple and the other measured in bytes, but maybe
> that's just exchanging one form of confusion for another.

We don't really have a good way to deal with GUCs where setting one
precludes the other, especially when those GUCs should be changable at
runtime :(.

Greetings,

Andres Freund