Re: [SQL] Interval subtracting

Tom Lane wrote:
> Mark Dilger <pgsql@markdilger.com> writes:
> 
>>This overall design seems more flexible than Tom's recent post in which he 
>>stated that justify_days should call justify_hours internally.
> 
> 
> AFAIR I said the exact opposite.
> 
>             regards, tom lane

Tom Lane also wrote:
> assumption), but justify_days should be changed to be effectively a
> combination of both functions --- that is, it should fix all three
> fields using both the 30days and the 24hours assumptions.  Then it could
> guarantee that all come out with the same sign.


How is changing justify days so that it touches the hours field different from 
having justify_days call justify_hours?

mark