[Koha-devel] 1 timezone system?

Thu May 5 07:08:30 CEST 2016

On Wed, May 4, 2016 at 11:15 PM, Mark Tompsett <mtompset at hotmail.com> wrote:

> Greetings,
>
> Sorry if I took something out of context to create a different thread.
>

I think that I may have highjacked the original thread. Apologies to David
Cook and Larry Letelier, and thank you for creating a thread specific to
this conversation.

> David Cook wrote:
> > “Maybe Koha is fine just being a 1 timezone system.”
>
> What I would prefer is a 1 timezone backend, with user specific timezone
> front-end with a default timezone.
> Why? Global consortia. The organization I work with has libraries
> across... 1,2,3, perhaps 4 time zones maybe 5.
> I could easily imagine it increasing in the future.
>

Instances with branches that span time zones is certainly not the most
common case, but it's an exception that's likely to bite someone in the
hind quarters. "Do you have branches in separate time zones" is not a
question that's likely to be asked in a pre-migration interview, and could
very possibly be a show-stopper. I could easily see this causing a lot of
wasted time, money and effort.

Koha is supposed to be a general purpose ILS, and I don't think that
limiting it to a

> GPML,
> Mark Tompsett
>
> P.S. Back to your regularly scheduled Y2038 doomsday discussion.
>
> *From:* David Cook <dcook at prosentient.com.au>
> *Sent:* Wednesday, May 04, 2016 8:23 PM
> *To:* 'Barton Chittenden' <barton at bywatersolutions.com>
> *Cc:* koha-devel at lists.koha-community.org
> *Subject:* Re: [Koha-devel] Invalid local time for date in time
> zone:America/Santiago
>
>
> Hey Barton,
>
>
>
> Yes, the year 2038 for timestamps is a problem even on 64 bit machines.
>
>
>
> Here’s a test you can do on a 64 bit MySQL install on a 64 bit OS:
>
>
>
> select unix_timestamp('2038-01-20');
>
> select from_unixtime(2548990800);
>
>
>
> Both will return null.
>
>
>
> You can also try storing a value of ‘2039-01-01’ into a timestamp column,
> and you’ll get the following message :
>
>
>
> Out of range value for column 'timestamp' at row 1
>
>
>
> Here’s some good explanations:
>
>
> http://askubuntu.com/questions/675116/timestamp-year-2038-problem-for-64-bit-ubuntu-system
>
> https://bugs.mysql.com/bug.php?id=12654
>
>
>
> Also, I’d never heard of date_t before your email, and the only references
> I can see to it are for specific projects which have implemented it as a
> new data structure themselves. I think time_t is the standard and that
> depends on your system architecture, although as you can see in those above
> links – it’s more complicated than that in MySQL.
>
>
>
> --
>
>
>
> issues.date_due is already a DATETIME data type, so we don’t need to worry
> about 2038. As for time zones, why would it be tricky storing it in UTC?
>
>
>
> At the moment, you can only have due dates in one time zone. That means
> you can’t have library systems spanning more than one timezone. Maybe
> that’s a rare or uncommon scenario, but here in the state of New South
> Wales, we actually do have 2 different timezones. In that case, when you’re
> doing a check out, you choose a local time, convert it to UTC for storage,
> and then render it in local time for the library user and library staff.
>
>
>
> I imagine the trickiest part would be the Reports module, as users
> wouldn’t know to use something like the CONVERT_TZ() function.
>
>
>
> Calculating overdues against holidays might be tricky… although that’s a
> case of just getting your timezone right as well. I reckon your timezone
> should be set per library, so you just fetch your UTC datetime, convert it
> to your local library timezone, probably convert it to floating to do math,
> and then convert it back to local timezone, and then whatever else you
> need. It sounds complex, but it’s really not that bad when you have it
> structured well.
>
>
>
> --
>
>
>
> Barton, I’m not sure I understand your reaction :p. I also field support
> tickets for a living, and I think it would be a lot easier to field tickets
> for a re-architected system that is created off years of experience rather
> than years of technical debt. Of course, I know re-architecting a system is
> also a lot easier said than done. But I think that’s why you see folks like
> EBSCO thinking about creating a microservice based system which can
> integrate with Koha. Incremental change.
>
>
>
> I suppose dates are most important when it comes to circulation and
> patrons… and I think that’s what people probably think about when they
> think of core Koha. I suppose acquisitions  and serials require a lot of
> careful date handling as well… I was actually thinking about Koha and
> “asset tracking” in general this morning on the way to the office.
>
>
>
> I don’t know. Maybe Koha is fine just being a 1 timezone system. I imagine
> library systems spanning over multiple timezones are probably the exception
> rather than the rule.
>
>
>
> We need to re-think some of our DateTime logic though. Whether we use
> ‘floating’ timezones more consistently, or are careful with creating local
> times that don’t exist…
>
>
>
>
>
> David Cook
>
> Systems Librarian
>
>
>
> Prosentient Systems
>
> 72/330 Wattle St
>
> Ultimo, NSW 2007
>
>
>
> Office: 02 9212 0899
>
> Direct: 02 8005 0595
>
>
>
> *From:* Barton Chittenden [mailto:barton at bywatersolutions.com]
> *Sent:* Thursday, 5 May 2016 12:04 AM
> *To:* David Cook <dcook at prosentient.com.au>
> *Subject:* Re: [Koha-devel] Invalid local time for date in time zone:
> America/Santiago
>
>
>
>
>
>
>
> On Thu, Apr 28, 2016 at 7:27 PM, David Cook <dcook at prosentient.com.au>
> wrote:
>
> I don’t think using “timestamp” would be preferable to “datetime”.
>
>
>
> First, MySQL’s timestamp seems to suffer from the Year 2038 problem (
> https://en.wikipedia.org/wiki/Year_2038_problem)(
> http://bugs.mysql.com/bug.php?id=12654), while datetime does not.
>
>
>
>
>
> Even on 64 bit machines?
>
>
>
> Oh MySQL, MySQL, knowest thou not of date_t?
>
>
>
> Second, you’d be handling timezones at the data level rather than at the
> application level. I’d rather have a convention of storing DATETIME as UTC,
> having Koha fetch that DATETIME as UTC, and then doing timezone conversions
> from there.
>
>
>
>
>
> I think that could be handled *relatively* transparently in DateUtils.pm,
> but there are a lot of corner cases like due dates that get ... tricky.
>
>
>
> As for the same server running different time zones, you can change the
> timezone on a per connection setting I think, but that could be a hassle. I
> think it would be easier just to store things clearly as UTC. This is done
> on a different project I work on, and it works well.
>
>
>
> Oh, I think it’ll be a nightmare changing timezone/timestamp/datetime
> handling in Koha. I don’t even know if it’s possible, to be honest. Well,
> it would be possible, but it would likely be an error-prone process.
>
>
>
> It’s things like this which make me think that we need to start thinking
> about a version of Koha that doesn’t have a clear upgrade path. A Koha with
> some major architectural changes which will need a skilled hand to migrate
> to. It won’t be nice for a lot of people… but I don’t know how else we’re
> going to make some major changes without dramas.
>
>
>
> From a design standpoint, I agree.
>
>
>
> From the point of view of someone who fields support tickets for a living:
>
>
>
> NOOOOOOOOOOOOOOOOOOOOO!!!!
>
>
>
> ... but that's just an emotional response.
>
>
>
> Cheers,
>
>
>
> --Barton
>
>
>
> ------------------------------
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