Re: proposal: rounding up time value less than its unit.

Gregory Smith <gregsmithpgsql@gmail.com> writes:
> On 9/26/14, 2:34 PM, David Johnston wrote:
>> ​ I don't get where we "need" to do anything else besides that...the 
>> whole "actual min values" comment is unclear to me.

> If you look at pg_settings, there is a minimum value exposed there as 
> min_val.  For some of these parameters, that number would normally be 
> 1.  But since we have decided that 0 is a special flag value, min_val is 
> 0 instead.

Right.

> There are others where min_val is -1 for the same reason, where 
> functionally the minimum is really 0.  Some of us would like to see 
> min_val reflect the useful minimum, period, and move all these special 
> case ones out of there.  That is a multi-year battle to engage in 
> though, and there's little real value to the user community coming out 
> of it relative to that work scope.

The impression I had was that Stephen was thinking of actually setting
min_val to 1 (or whatever) and handling zero or -1 in some out-of-band
fashion, perhaps by adding GUC flag bits showing those as allowable
special cases.  I'm not sure how we would display such a state of affairs
in pg_settings, but other than that it doesn't sound implausible.

We could alternatively try to split up these cases into multiple GUCs,
which I guess is what you're imagining as a "multi-year battle".  But
personally I think any such proposal will fail on the grounds that
it's too much compatibility loss for the value gained.
        regards, tom lane