Re: proposal: rounding up time value less than its unit. - Mailing list pgsql-hackers

From David G Johnston
Subject Re: proposal: rounding up time value less than its unit.
Date
Msg-id 1408654735557-5815770.post@n5.nabble.com
Whole thread Raw
In response to Re: proposal: rounding up time value less than its unit.  (Peter Eisentraut <peter_e@gmx.net>)
List pgsql-hackers
Peter Eisentraut-2 wrote
> On 8/21/14 11:16 AM, Tom Lane wrote:
>> Heikki Linnakangas <

> hlinnakangas@

> > writes:
>>> The patch also rounds a zero up to one. A naked zero with no unit is not 
>>> affected, but e.g if you have "log_rotation_age=0s", it will not disable 
>>> the feature as you might expect, but set it to 1 minute. Should we do 
>>> something about that?
>> 
>> That sounds like a dealbreaker to me.  There are enough places where zero
>> has special meaning that we should not *ever* change zero to non-zero
>> silently.
> 
> I don't think I like this idea anyway.  If something has units of an
> hour and the user (perhaps misunderstanding the setting) sets it to one
> second, then we shouldn't silently change that to one hour.
> 
> If there is a problem with rounding it to zero, then we should perhaps
> raise an error.  (And stop treating zero specially.  It's a terrible
> idea.)

I'm on board, from the original thread, for errors if the input cannot be
converted to the parameter measurement unit cleanly.  By which I mean the
specified value should result in an integer being recorded without rounding. 
Specifying a precision less than the default unit thus becomes impossible.

I don't have a problem with zero meaning disabled when appropriate since it
avoids having a separate on/off GUC.

That said the complaint here just seems like a bug in the supplied patch -
zero is zero regardless of whether a unit is specified.  The only obvious
exception would be temperature but that isn't relevant here.

David J.



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