Re: [SQL] Interval subtracting

Tom Lane wrote:
> Mark Dilger <pgsql@markdilger.com> writes:
> 
>>justify_days(justify_hours(...)) fixes *everything* in the most recently 
>>submitted patch, regardless of the convoluted case you invent.  There is no data 
>>for which it won't work.
> 
> 
> If so, one function or the other is cheating.  Per discussion,
> justify_hours must never touch months, and I don't believe that
> justify_days should touch seconds either.  The proposed justify_interval
> function should have a result different from successive application
> of the two existing functions, because it will ensure that all three
> fields have similar signs whereas separate use of the two functions
> can't promise that in corner cases.
> 
>             regards, tom lane
> 
> ---------------------------(end of broadcast)---------------------------
> TIP 2: Don't 'kill -9' the postmaster
> 

That depends what you mean by cheating.  The justify_hours function looks to see 
what answer justify_days would give, but does not actually change the data.  I 
described this all earlier and I still don't see why there is anything wrong 
with it.

mark