Thread: Re: [BUGS] BUG #1993: Adding/subtracting negative time intervals
[ bugs list removed, hackers added.]
Tom Lane wrote:
> Bruce Momjian <pgman@candle.pha.pa.us> writes:
> > I saw a lot of disussion because I forgot to specify that my tests were
> > for EST5EDT, but what about the use of interval_justify_hours() in
> > timestamp_mi(). Is this something we want to change?
>
> It's too late to mess with it for 8.1, but see my previous message
> proposing a set of TODO items for future work.
Yes, it is late, but I am worried about adding an interface change that
we will later revert in 8.2. In 8.0.X I see the query returning the '25
hour' answer:
SELECT('2005-10-29 13:22:00-04'::timestamptz +('2005-10-30 13:22:00-05'::timestamptz - '2005-10-29
13:22:00-04'::timestamptz))at time zone 'EST'; timezone--------------------- 2005-10-30 13:22:00(1 row)
In current CVS the top query returns '14:22:00'. Do we change this for
8.1, then change it back in 8.2? That seems bad to me.
Actually, 8.0.X returns '1 day, 1 hour' for the subtraction, which we
treat in 8.0.X as '25 hours':SELECT ('2005-10-30 13:22:00-05'::timestamptz - '2005-10-29
13:22:00-04'::timestamptz); ?column?---------------- 1 day 01:00:00(1 row)
In 8.0.X, because we didn't have a 'days' field, we could treat '1 day 1
hour' as always '25 hours', and could display the results as days/hours.
If we remove interval_justify_hours(), then we are always going to
display timestamp subtraction in hours (not days), e.g. '6422 hours'
(yea, ugly) unless they manually call interval_justify_hours().
Keep in mind that the addition of the interval_justify_hours() did
generate some regression test changes, so removing
interval_justify_hours() might just take the results back to what we had
in 8.0. My point is that regression changes caused by its removal might
not be a good guide to determining compatibility with 8.0.X.
I guess my point is that we are changing 8.0.X behavior so we better be
sure it is now the way we want it to remain.
-- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610)
359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square,
Pennsylvania19073
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Keep in mind that the addition of the interval_justify_hours() did
> generate some regression test changes, so removing
> interval_justify_hours() might just take the results back to what we had
> in 8.0.
Not hardly. I tried already. The existing timestamp_mi behavior is
probably as close to 8.0 as we can get given the change in underlying
representation.
> I guess my point is that we are changing 8.0.X behavior so we better be
> sure it is now the way we want it to remain.
[ shrug... ] We've changed datetime behavior in every past release,
we're changing it for 8.1, we'll probably change it some more for 8.2,
and again after that. All the datetime code is a work in progress.
Get used to it.
regards, tom lane
Tom Lane wrote: > Bruce Momjian <pgman@candle.pha.pa.us> writes: > > Keep in mind that the addition of the interval_justify_hours() did > > generate some regression test changes, so removing > > interval_justify_hours() might just take the results back to what we had > > in 8.0. > > Not hardly. I tried already. The existing timestamp_mi behavior is > probably as close to 8.0 as we can get given the change in underlying > representation. You mean the '6432 hours' is a worse change, OK. > > I guess my point is that we are changing 8.0.X behavior so we better be > > sure it is now the way we want it to remain. > > [ shrug... ] We've changed datetime behavior in every past release, > we're changing it for 8.1, we'll probably change it some more for 8.2, > and again after that. All the datetime code is a work in progress. > Get used to it. OK, as long as we are sure we are not going to change it back to 8.0 behavior. -- Bruce Momjian | http://candle.pha.pa.us pgman@candle.pha.pa.us | (610) 359-1001+ If your life is a hard drive, | 13 Roberts Road + Christ can be your backup. | Newtown Square, Pennsylvania19073
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> Tom Lane wrote:
>> Not hardly. I tried already. The existing timestamp_mi behavior is
>> probably as close to 8.0 as we can get given the change in underlying
>> representation.
> You mean the '6432 hours' is a worse change, OK.
Well, it's sure not a small change, and we're still undecided whether
that's what we want in the long run.
Also, we'd have to deal with some of the other TODO items I mentioned
before we could make it work at all. There's at least one regression
test that computes an interval larger than 2^31 hours (how do you think
I found out about that problem ;-))
regards, tom lane