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From: Jim Nasby <jimn@enterprisedb.com>
Subject: Re: [HACKERS] timestamp subtraction (was Re: formatting intervals
	with to_char)
Date: Thu, 5 Oct 2006 21:40:57 -0500
To: Tom Lane <tgl@sss.pgh.pa.us>

On Oct 5, 2006, at 11:50 AM, Tom Lane wrote:
> regression=# select ('2006-09-15 23:59:00'::timestamp - '2006-09-01  
> 09:30:41'::timestamp);
>      ?column?
> ------------------
>  14 days 14:28:19
> (1 row)
>
> should be reporting '350:28:19' instead.
>
> This is a hack that was done to minimize the changes in the regression
> test expected outputs when we changed type interval from months/ 
> seconds
> to months/days/seconds.  But I wonder whether it wasn't a dumb idea.
> It is certainly inconsistent, as noted in the code comments.
>
> I'm tempted to propose that we remove the justify_hours call, and tell
> anyone who really wants the old results to apply justify_hours() to  
> the
> subtraction result for themselves.  Not sure what the fallout would  
> be,
> though.

I suspect there's applications out there that are relying on that  
being nicely formated for display purposes.

I agree it should be removed, but we might need a form of backwards  
compatibility for a version or two...
--
Jim Nasby                                    jimn@enterprisedb.com
EnterpriseDB      http://enterprisedb.com      512.569.9461 (cell)