Re: [PATCH] Integer overflow in timestamp[tz]_part() and date/time boundaries check

Mark Dilger <hornschnorter(at)gmail(dot)com> writes:
>> On Mar 14, 2016, at 5:12 PM, Vitaly Burovoy <vitaly(dot)burovoy(at)gmail(dot)com> wrote:
>> I don't think it is real, and even in such case all constants are
>> collected together in the file and will be found and changed at once.

> I agree that they would be found at once. I disagree that the example
> is not real, as I have changed the postgres epoch myself in some builds,
> to be able to use int32 timestamps on small devices.

I concur with Vitaly that it's not this patch's job to make it easier to
change the epoch date. If you want to submit a patch for that purpose,
you're welcome to.

I have a bigger problem though: I see that the patch enforces AD 294277
as the endpoint for both integer and floating-point datetimes. This
contradicts the statement in the docs (section 8.5) that

Note that using floating-point datetimes allows a larger range of
timestamp values to be represented than shown above: from 4713 BC up
to 5874897 AD.

Since that is just about the only non-historical reason why somebody might
wish to use float timestamps, I'm rather reluctant to remove the feature,
especially without any discussion --- and I don't see any discussion of
this point upthread.

My feeling is we ought to preserve the old behavior here, which would
involve making JULIAN_MAXYEAR_FOR_TIMESTAMPS format-dependent and
adjusting the float values for the two derived constants; not much of a
problem code-wise. I think though that it would break quite a number of
the proposed new regression tests for the float case. TBH, I thought
the number of added test cases was rather excessive anyway, so I wouldn't
have a problem with just leaving out whichever ones don't pass with both
build options.

Comments?

regards, tom lane