Thread: Re: [PATCHES] [BUGS] BUG #3326: Invalid lower bound of autovacuum_cost_limit

Tom Lane wrote:
> Alvaro Herrera <alvherre@commandprompt.com> writes:
> > But this is misleading (started postmaster with good value, then edited
> > postgresql.conf and entered "-2"):
>
> > 17903 LOG:  received SIGHUP, reloading configuration files
> > 17903 LOG:  -2 is outside the valid range for parameter "autovacuum_vacuum_cost_limit" (-1 .. 1000)
>
> > Note how it still says the range is -1 .. 1000.
>
> Can we redefine things to make zero be the "disabled" value, thus
> keeping the range of valid values contiguous?

That would be another solution ... though it would be different from the
valid value for autovacuum_vacuum_cost_delay (on which 0 is a valid
value).  Also it would be a different value from previous versions.

I don't think either of these is a showstopper, so let's go for that if
nobody objects.

--
Alvaro Herrera                          Developer, http://www.PostgreSQL.org/
<inflex> really, I see PHP as like a strange amalgamation of C, Perl, Shell
<crab> inflex: you know that "amalgam" means "mixture with mercury",
       more or less, right?
<crab> i.e., "deadly poison"

Alvaro Herrera wrote:
> Tom Lane wrote:
>> Alvaro Herrera <alvherre@commandprompt.com> writes:
>>> But this is misleading (started postmaster with good value, then edited
>>> postgresql.conf and entered "-2"):
>>> 17903 LOG:  received SIGHUP, reloading configuration files
>>> 17903 LOG:  -2 is outside the valid range for parameter "autovacuum_vacuum_cost_limit" (-1 .. 1000)
>>> Note how it still says the range is -1 .. 1000.
>> Can we redefine things to make zero be the "disabled" value, thus
>> keeping the range of valid values contiguous?
>
> That would be another solution ... though it would be different from the
> valid value for autovacuum_vacuum_cost_delay (on which 0 is a valid
> value).  Also it would be a different value from previous versions.
>
> I don't think either of these is a showstopper, so let's go for that if
> nobody objects.

Can you make 0 and -1 both valid disabled values?  That way it will be
compatible with previous releases.

Matthew T. O'Connor wrote:
> Alvaro Herrera wrote:
> >Tom Lane wrote:
> >>Alvaro Herrera <alvherre@commandprompt.com> writes:
> >>>But this is misleading (started postmaster with good value, then edited
> >>>postgresql.conf and entered "-2"):
> >>>17903 LOG:  received SIGHUP, reloading configuration files
> >>>17903 LOG:  -2 is outside the valid range for parameter
> >>>"autovacuum_vacuum_cost_limit" (-1 .. 1000)
> >>>Note how it still says the range is -1 .. 1000.
> >>Can we redefine things to make zero be the "disabled" value, thus
> >>keeping the range of valid values contiguous?
> >
> >That would be another solution ... though it would be different from the
> >valid value for autovacuum_vacuum_cost_delay (on which 0 is a valid
> >value).  Also it would be a different value from previous versions.
> >
> >I don't think either of these is a showstopper, so let's go for that if
> >nobody objects.
>
> Can you make 0 and -1 both valid disabled values?  That way it will be
> compatible with previous releases.

Heh, sure, we can do that too and it doesn't seem like anybody would
object.  I will patch the documentation so that that the "disabled"
value is zero, and still allow -1.  That way it doesn't seem like there
should be any objection.

--
Alvaro Herrera                         http://www.flickr.com/photos/alvherre/
"Escucha y olvidarás; ve y recordarás; haz y entenderás" (Confucio)

Alvaro Herrera wrote:
> Matthew T. O'Connor wrote:

> > Can you make 0 and -1 both valid disabled values?  That way it will be
> > compatible with previous releases.
>
> Heh, sure, we can do that too and it doesn't seem like anybody would
> object.  I will patch the documentation so that that the "disabled"
> value is zero, and still allow -1.  That way it doesn't seem like there
> should be any objection.

Patch attached.

--
Alvaro Herrera                  http://www.amazon.com/gp/registry/5ZYLFMCVHXC
"Saca el libro que tu religión considere como el indicado para encontrar la
oración que traiga paz a tu alma. Luego rebootea el computador
y ve si funciona" (Carlos Duclós)

Alvaro Herrera <alvherre@commandprompt.com> writes:
>> Matthew T. O'Connor wrote:
>>> Can you make 0 and -1 both valid disabled values?  That way it will be
>>> compatible with previous releases.
>>
>> Heh, sure, we can do that too and it doesn't seem like anybody would
>> object.  I will patch the documentation so that that the "disabled"
>> value is zero, and still allow -1.  That way it doesn't seem like there
>> should be any objection.

> Patch attached.

It seems like documenting vac_cost_limit as being different from the
others will just create perceived complexity/confusion, with no real
benefit.  I'd suggest leaving the documentation and the default value
alone, and applying just the part of the patch that causes 0 to be
silently treated as if it were -1.

A comment at the spot where this is done would be a good idea, but
I don't think we need to say anything in the SGML docs.

            regards, tom lane