On AIX timestamp and horology regression fails in current, because 
timestamp - interval for result timestamps that are before 1970 (epoch ?) 
are off by one hour. I think this is not an issue for an adapted expected file, 
but a new (in 7.1beta) bug. But I am at no means an expert at what the result 
should be when substracting 34 years from epoch or 'Mon Dec 30 17:32:01 1996 PST'.

Andreas
Tue, 9 Jan 2001 10:44:21 +0100 
Zeugswetter Andreas SB  <ZeugswetterA@wien.spardat.at>
tinterval - operator problems on AIX
> On AIX timestamp and horology regression fails in current, because
> timestamp - interval for result timestamps that are before 1970 (epoch ?)
> are off by one hour. I think this is not an issue for an adapted expected file,
> but a new (in 7.1beta) bug. But I am at no means an expert at what the result
> should be when substracting 34 years from epoch or 'Mon Dec 30 17:32:01 1996 PST'.

Hi Andreas. It is certainly true that the behavior has changed for the
new release, but afaik it can not be put into the "bug" category.

The difference is that, before, I rotated date/time into the correct
time zone for arithmetic by adding/subtracting the current time zone.
For (date/time)-(interval), this resulted in evaluating the result in
the same time zone as the starting date/time, which was not correct.

The time zone is now evaluated in the time zone of the result, rather
than the input, using system support routines from libc. But that will
expose troubles on some platforms with time zone support before 1970.
Some platforms are worse than others; my experience has been that
zinc-based systems such as Linux, FreeBSD, and Tru64 are pretty good,
Suns are the best, and, well, apparently AIX is not ;)

                       - Thomas

Tue, 09 Jan 2001 15:06:03 +0000
Thomas Lockhart <lockhart@alumni.caltech.edu>
Re: tinterval - operator problems on AIX