The time zone database (date_time_zonespec.csv or boost_1_55_0/libs/date_time/data/date_time_zonespec.csv) of boost::date_time library seems not to be up to date. Is there a way to generate it from latest version of IANA time zone database?
This should be the answer found in boost::locale reference:
Why don't you use Boost.DateTime time zone support?
Boost.DateTime's time zone support is broken. Time zones can not be
represented with a simple table of rules where daylight saving depend
only on certain n'th day of week in month. The daylight savings time
may vary by year, political issues and many other things.
There is also the new C++20 date functions, added to the chrono lib. It can use your system's TZ database, at least on Linux/Mac, or you can have the library automatically download the latest TZ to a folder instead. You can try it out here: https://github.com/HowardHinnant/date
Related
Currently my laravel config time zone is set to '+6:00' and MariaDB database time zone is set to SYSTEM, which is +6:00 as well. Now that I need to accommodate users from different time zones, I need to migrate all timestamp values to UTC to avoid any unintended time-related issues.
In MariaDB documentation it is stated that: https://mariadb.com/kb/en/timestamp/#time-zones
If a column uses the TIMESTAMP data type, then any inserted values are
converted from the session's time zone to Coordinated Universal Time
(UTC) when stored, and converted back to the session's time zone when
retrieved.
Now, this is where I am getting confused. What I understand from the above statement that I do not require to change anything in the database as timestamps are always stored in UTC no matter what is my session time zone is at the time of saving the data. Therefore, later on if I update my time zone to UTC in Laravel config, I should get the corresponding UTC value. But after changing the Time zone to UTC in Laravel config I am still getting the time in +6:00 format from eloquent model.
I think I am missing something here and would really appreciate any suggestion regarding this. Thanks in advance.
we have iot devices deployed on customer locations of different parts of the world. it should give some printed monitoring data in Daily weekly and monthly reports in our web dashboard. the issue is some timezones have day light savings, so these customers demand it should be based on dst.
what we want to try is
get a list of timezones we use
whenever there is a dst update in the timezone update the time on the device
but we can find how to fire an event for dst updates in different timezones, we can use python, ruby or shell or any command line tools that helps.
UPDATE
based on #rici 's answer i googled about zdump and found this
https://superuser.com/questions/805185/linux-command-to-check-wherever-this-day-is-a-dst-change-day-and-which-direction
this answer will give when DST starts and ends.
what i now do is manually set crontab based on these data.
how can i automate scheduling tasks?
You can use the zdump utility to print the current time in a liat of zones. If you do that every hour, and check the DST indicator against the previous output, you will see which zones have changed.
I have no idea how you can figure out which tmezones are important or how you identify which devices are in which time zone.
I'm working on optimizing some functions in which I need to convert many timestamps to UTC. My need is to create a table with the columns as follows:
YEAR | TZ_NAME | Start of Daylight Savings | End of Daylight Savings
I can convert the timestamps easily using the from_tz function in oracle, however running this per timestamp isn't an option. Does anyone know how the oracle function works? I can't find any documentation that details where oracle keeps these daylight savings rules.
Any suggestions?
Thank you!
The time zone related information is stored in a file, as per: https://docs.oracle.com/cd/B19306_01/server.102/b14225/ch4datetime.htm#i1006667
The Oracle time zone files contain the valid time zone names. The
following information is also included for each time zone:
•Offset from Coordinated Universal Time (UTC)
•Transition times for Daylight Saving Time
•Abbreviations for standard time and Daylight Saving Time
I am actually using the mongDB API via a tLibraryLoad component, as I find this easier to build complex multi-level documents using tJavaRow and tJava components, than using the MongoDB palette components.
I am reading in data from Oracle which are date values with a zero time stamp component: For example:
29-JUN-08 00.00.00
The import works via Talend, however the records in mongo shell appear to be the previous day. You can see the record is inserted as the 28-JUN-2008.
Extract from JSON document in mongoDB:
"status_date" : ISODate("2008-06-28T23:00:00Z")
It is almost as if mongoDB (or Talend?) sees a midnight date as the end of the previous day, rather than the start of the 29th June 2008.
In my Talend schema I have specified the Oracle columns as Date types with a DB Type of Date also.
Any advice appreciated.
---UPDATE 1------
As only some dates are affected, it seems this is a DST adjustment in mongoDB to adjust perhaps the display to my local timezone, as the dates which are impacted are in the back half of the year in daylight saving time.
Is it adjusting the date due to the location of the mongo shell?
It is adjusting the date due to the location of the mongo server so all people using the mongo shell would get the same answers to date queries?
Would different people running different mongo queries on dates get different results based on their location, their DST kick in dates...i.e. you could imagine dates from the 1st November 2015, being counted as contributing to October 31st figures (at 23:00)....
i
I feel your pain - this is derived from MongoDB itself.
At issue is that MongoDB stores dates in UTC format by default.
https://docs.mongodb.org/manual/tutorial/model-time-data/
You can use Mongo's suggestion above but in this case you are storing just the date and not the time. I've used two solutions:
Don't bother storing dates as DATEs. Convert all your dates to %Y%m%d format and store them as integers. You can easily compare dates using $gt and $lte just using integers - just be sure to bring in your date using the same format and convert them back in your program later.
... or ...
Since in your case your date seems to be off by an hour, add an hour to it before you make your insert. It all depends on how long the timezone offset is to your local machine.
On linux you can see what the utc value is using:
date -u
I suppose you could change your local timezone on your machine to be UTC time and see what happens.
Personally, I've never had an issue with using the first approach. It's fast and ensures that I have what I want in there.
I think it is because of the timezone of your server. Try to remove the timezone from your date object and then insert it to the mongodb.
With moment.js you can create date without the timezone in such way:
var date = moment.utc("29-JUN-08 00.00.00", 'DD-MM-YYYY h.mm.s').format()
Does golang's time package (or any other library) support the concept of a local date?
By local date, I'm referring to the concept supported by joda time, which is a date without a time or timezone.
The package you refer to uses UTC :
This chronology will be set internally to be in the UTC time zone for all calculations.
You can simply get the UTC time using the time package and do calculations on that.