[tz] DST ends 2040 in Oracle database

Joachim Damm Joachim.Damm at werum.com
Fri Jan 25 07:53:27 UTC 2019

Dear Paul,

I am looking for America/New_York and I got the information from Oracle that tzdata from IANA are almost till 2040.
My question is, is that correct?
And, if this is correct, is there any plan to fix this?

For the reason of my question, we are a software company and in our software the customer is able to calculate an expiry date. Now, the first customer (in the US) build a product with an expiry date in 2046 and we see, that the calculation from Oracle is wrong.
I have created a SR at Oracle and the support tell me the following:

"Please note that Oracle database pick up tzdata from IANA and the tzdata available are mostly till 2040 only.
As mentioned earlier the DST patches contains rules till 2040, as of now which needs to be extended DST files past the year 2040
This is known issue which will be fix in future with below enhancement request raised."

Can you confirm the statement from Oracle or is it wrong?

Mit freundlichen Grüßen / Kind Regards

i.A. Joachim Damm

Senior Database Consultant Systems Integration

Werum IT Solutions GmbH
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T +49 4131 8900-515
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-----Original Message-----
From: Paul Eggert [mailto:eggert at cs.ucla.edu] 
Sent: Donnerstag, 24. Januar 2019 19:31
To: Joachim Damm <Joachim.Damm at werum.com>; Time Zone Mailing List <tz at iana.org>
Subject: Re: [tz] DST ends 2040 in Oracle database

On 1/24/19 2:05 AM, Joachim Damm wrote:
> we found one issue in the Oracle database that DST calculation is 
> wrong from 2040 and beyond.

Which DST calculation, exactly, and what are the incorrect and correct values?

Perhaps you're thinking about Brazil, Iran, or Morocco. In these countries DST rules are so complex that they cannot be expressed in closed form in the tzdb notation, so tzdb lists rules explicitly for each year. Eventually this list has to stop, though, as the database and its maintainers' patience are finite. For Brazil and Morocco the list of exact predictions stops after 2037; for Iran, 2087.

Brazil and Morocco keep changing their DST rules, so any prediction past this year (much less past 2037) is dubious anyway. In contrast, Iran's rules have been stable since 2008, so I extended its exact prediction to 2087; there is some technical confusion about how to interpret Iran's rules after that, and even Iran is likely to change its rules before 2087.

If there's a real need to predict past 2037, what is the need and how far does it really go?

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