> 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.
Timestamps have a unit from SECOND to NANOSECOND, but otherwise they are stored as a 64-bit signed integer. I agree it would be good to put the minimum and maximum values in the spec On Fri, Mar 17, 2017 at 4:23 PM, Julian Hyde <jh...@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 <wesmck...@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 >
