Re: Cost limited statements RFC

On 2013-06-06 12:34:01 -0700, Jeff Janes wrote:
> On Fri, May 24, 2013 at 11:51 AM, Greg Smith <greg(at)2ndquadrant(dot)com> wrote:
>
> > On 5/24/13 9:21 AM, Robert Haas wrote:
> >
> > But I wonder if we wouldn't be better off coming up with a little more
> >> user-friendly API. Instead of exposing a cost delay, a cost limit,
> >> and various charges, perhaps we should just provide limits measured in
> >> KB/s, like dirty_rate_limit = <amount of data you can dirty per
> >> second, in kB> and read_rate_limit = <amount of data you can read into
> >> shared buffers per second, in kB>.
> >>
> >
> > I already made and lost the argument for doing vacuum in KB/s units, so I
> > wasn't planning on putting that in the way of this one.
>
>
> I think the problem is that making that change would force people to
> relearn something that was already long established, and it was far from
> clear that the improvement, though real, was big enough to justify forcing
> people to do that.

I don't find that argument very convincing. Since you basically can
translate the current variables into something like the above variables
with some squinting we sure could have come up with some way to keep the
old definition and automatically set the new GUCs and the other way
round. guc.c should even have enough information to prohibit setting
both in the config file...

Greetings,

Andres Freund

--
Andres Freund http://www.2ndQuadrant.com/
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