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From Julien Le Dem <jul...@dremio.com>
Subject Re: Making some decisions about date and time types
Date Fri, 17 Mar 2017 23:26:10 GMT
> At some point someone will want MONTH as a time unit (to support SQL’s
year-to-month interval type)
There is an interval type here for that:
https://github.com/apache/arrow/blob/39c7274fc36b5f405f1dbfa48067dde52abec5ce/format/Message.fbs#L98

On Fri, Mar 17, 2017 at 1:23 PM, Julian Hyde <jhyde@apache.org> wrote:

> Am I correct that timestamp is a 64 bit signed integer representing
> microseconds since 1970? If so, it would be helpful to state the minimum
> and maximum values in the spec.
>
> I can’t quite imagine a use case for microsecond time, given that it takes
> the same number of bits as a timestamp. But still, no harm in including it.
>
> At some point someone will want MONTH as a time unit (to support SQL’s
> year-to-month interval type) and someone will want nanosecond timestamp
> (problematic, because it needs more than 64 bits for a useful range to
> dates). But these can wait until version 2.
>
> Julian
>
>
> > On Mar 17, 2017, at 9:51 AM, Wes McKinney <wesmckinn@gmail.com> wrote:
> >
> > hi folks,
> >
> > We have some format decisions to make about all 3 of the primary
> > temporal types in Arrow:
> >
> > ARROW-617 - Time type
> > - It is proposed to add the type bit width to the metadata for
> > clarity, and using the smallest type that can accommodate a particular
> > time unit
> > - PATCH: https://github.com/apache/arrow/pull/385
> >
> > ARROW-316: Date type
> > - It is proposed to add a DateUnit to indicate day-based date (a la
> > PostgreSQL and other systems) as int32 vs. millisecond-based date as
> > int64 (a la Joda, and current Arrow Java)
> > - PATCH: https://github.com/apache/arrow/pull/390
> >
> > ARROW-637: Timestamp type
> > - It is proposed to add a timezone string to the metadata as to
> > disambiguate TZ-naive vs. TZ-aware data, but otherwise display only
> > (changing the time zone does not alter the physical int64 timestamp
> > values)
> > - PATCH: https://github.com/apache/arrow/pull/388
> >
> > There seems to be some degree of consensus on all 3 of these, but it
> > would be good to reach a final decision and merge patches so that we
> > can do the corresponding dev work in Java and C++, and hopefully get
> > integration tests working in time for the Arrow 0.3 release.
> >
> > Thanks!
> > Wes
>
>


-- 
Julien

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