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From "Till Westmann" <ti...@apache.org>
Subject Re: Round Tripping ADM Interval Data
Date Tue, 26 Jan 2016 01:36:35 GMT
Voting for a. Seems to be the least redundant option.

Cheers,
Till

On 25 Jan 2016, at 16:47, Eldon Carman wrote:

> The interval field value printed in the ADM results can not be used to
> create an interval.
>
> Intervals have several functions that are used to construct an 
> interval:
> interval-from-date/time/datetime
> and interval-start-from-date/time/datetime. It appears that this is 
> the
> only way to create an interval. Thus, a user must use one of these 
> function
> to create an interval.
>
> The following query shows how to create three intervals.
>
> Query:
> let $di := {"date-interval": interval-from-date("2012-01-01", 
> "2013-04-01")}
> let $ti := {"time-interval": interval-from-time("12:23:34.456Z",
> "233445567+0800")}
> let $dti := {"datetime-interval":
> interval-from-datetime("2012-01-01T12:23:34.456+08:00",
> "20130401T153445567Z")}
> return [$di, $ti, $dti];
>
> Result:
> { "date-interval": interval-date("2012-01-01, 2013-04-01") }, {
> "time-interval": interval-time("12:23:34.456Z, 15:34:45.567Z") }, {
> "datetime-interval": interval-datetime("2012-01-01T04:23:34.456Z,
> 2013-04-01T15:34:45.567Z") } ]
>
> Notice the results show interval-date("date, date") which is different 
> than
> the functions that are used to create a date interval. Notice that
> interval-date does not exists in AsterixDB and that the input is a 
> single
> string of dates separated by a comma. Below are some ideas on how to 
> create
> a round-trip for intervals.
>
> Options for round tripping:
> a: Rename "interval-from-date" to "interval-date" and update the 
> output to
> put both dates in quotes.
> b: Add alias for "interval-from-date" to "interval-date" and update 
> the
> output to put both dates in quotes.
> c: Create an interval date constructor (called interval-date) that can
> parse the string "date, date".
>
> The same process should be used for intervals with time and datetime.
>
> Thoughts?

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