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Comment: Published by Scroll Versions from space DEV and version r093

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D s product
rtrue
 supports a variety of date-time Datetime formats, each of which has additional variations to it.

Date Range

Supported Date Ranges:  

  • Earliest: January 1, 1400

    Info

    NOTE: Two-digit values for the year that are older than 80 years from the current year are forward-ported into the future in

    D s product
    . This behavior may be different from source and target systems. See "Two-digit year values" below.

  • Latest: December 31, 2599


You can use dates in the Gregorian calendar system only. Dates in the Julian calendar are not supported.

Data Validation

When values are validated against the Datetime data type, the

D s webapp
does not compare them to an underlying calendar system. Instead, the application validates the values using regular expressions. This regular expression method checks for general Datetime validation and is fast to evaluate.

However, some values may follow the regular expression validation pattern but are not accurate dates. For example, every four years, February 29 is a valid date. When this date is validated against the Datetime data type, it may be detected as a valid value, while the date is changed in the application to be incremented to a close accurate date, such as March 1 in this example.

Formatting Tokens

You can use the following format strings tokens to change the format of a column of dates:

LetterDate or Time ComponentPresentationExamples
MMonth in yearNumber1
MMMonth in yearNumber01
MMMMMonth in yearMonthJanuary
MMMMonth in yearMonthJan
yyYearNumber

16

Info

NOTE: Two-digit values for the year that are older than 80 years from the current year are forward-ported into the future in

D s product
. This behavior may be different from source and target systems. See "Two-digit year values" below.

yyyyYearNumber2016
DDay in yearNumber352
dDay in monthNumber9
ddDay in a monthNumber09
EEE Day in week (three-letter abbreviation)TextWed
EEEEDay in weekTextWednesday
h

Hour in day (1-12)

Info

NOTE: Requires an AM/PM indicator (a).

Number2
hh

Hour in am/pm (01-12)

Info

NOTE: Requires an AM/PM indicator (a).

Number02
HHour in day (1-12)Number2
HHHour in day (0-23)Number20
mMinute in an hourNumber9

mm

Minute in an hourNumber09
sSecond in a minuteNumber3
ssSecond in a minuteNumber03
SSS MillisecondNumber218
XTime zoneISO 8601 time zone-08:00
aAM/PM indicatorStringAM
Info

NOTE: When publishing to relational targets, Datetime values are written as date/time values in newly created tables. If you are appending to a relational table column that is in timestamp format, Datetime values can be written as timestamps.

Tip

Tip: If your DateTime column contains data in multiple formats, you must change the format of the DateTime column to one format and then add a transform transformation to convert that data to the other format. When all formats of your source date values are converted to a single format, the application should infer the appropriate date and time format.

...

  • Support for timezone offset from UTC indicated by +hh:mm, +hhmm, or +hh. For example, the date '2013-11-18 11:55-04:00' is recognized as a DateTime value.

  • Datetime part functions (for example, Hour) truncate time zones and return local time.
  • If you have a column with multiple time zones, you can convert the column to Unixtime so you can perform Date/Time operations with a standardized time zone using the UNIXTIME function. If you want to work with local times, you can truncate the time zone or use other Datetime functions. See UNIXTIME Function.

...

Two-digit year values

Depending on the system, a two-digit value for year in a Datetime value is subject to different interpretations. In 

D s product
two-digit values for the year that are older than 80 years from the current year are forward-ported into the future. For example, in a job run on Dec 31, 2021, the date 01/01/41 is interpreted as 01/01/1941. However, if the job is run the next day (January 01, 2022), then the same data is interpreted as 01/01/2041.

Other systems use different limits for backward versus forward porting of year values:

As a result, it can be a challenge to manage these system-dependent two-digit years in a consistent manner. 

Tip

Tip: For best results, you should format year values as four-digit values before the data is ingested into

D s product
. Four-digit years are consistently represented across all systems.

If the above is not possible, you can create replacement steps in your recipe to convert two-digit years to four-digit values. In the following example, 00-39 is interpreted as a 19XX year, while 40-99 is interpreted as a 20XX year: 

D trans
RawWrangletrue
p03Value19$1
Typestep
WrangleText##NO_WRANGLE##
p01NameColumn
p01ValuemyDateColumn
p02NameFind
p02Value/\b([456789][0-9])\b$/
p03NameReplace with
SearchTermReplace text or pattern

and

D trans
RawWrangletrue
p03Value20$1
Typestep
WrangleText##NO_WRANGLE##
p01NameColumn
p01ValuemyDateColumn
p02NameFind
p02Value/\b([0123][0-9])\b$/
p03NameReplace with
SearchTermReplace text or pattern

Supported Datetime Formats

For more information on the available formats and examples of each one, see Datetime Formats (PDF).

You can use the DATEFORMAT function to modify the formatting of your Datetime values.

Supported Time Zones

Time zones values (e.g. UTC-08:00) are supported. 

Job Execution

Datetime data typing involves the basic type definition, plus any supported formatting options. Depending on where the job is executed, there may be variation in how the Datetime data type is interpreted. 

  • Some running environments may perform additional inference on the typing.

    Info

    NOTE: During job execution on Spark, inputs of Datetime data type may result in row values being inferred for data type individually. For example, the String value 01/10/2020 may be inferred by date transformations as 1st Oct, 2020 or 10th Jan, 2020. Resulting outputs of Datetime values may not be deterministic in this scenario.

  • Some formatting options may not be supported. 

Differences between 
D s photon
 and Spark running environments

If your Datetime data does not contain time zone information, by default:

  • Spark uses the time zone of the 

    D s item
    itemnode
     for Datetime values.

    Tip

    Tip: This use of time zone applies to any Spark-based running environment, such as EMR.

  • D s photon
     uses the UTC time zone for Datetime values.

This difference in how the values are treated can result in differences in Datetime-based calculations, such as the DATEDIF function.

Workarounds:

You can do one of the following:

  • Set the time zone for the 
    D s item
    itemnode
     to be UTC. You must also set the time zone for your Spark running environment to UTC.
  • Apply the following Spark execution properties from the Run Job page:

    Code Block
    "spark": 
      "props": {
        ...
        "spark.driver.extraJavaOptions" : "-Duser.timezone=\"UTC\"",
        "spark.executor.extraJavaOptions" : "-Duser.timezone=\"UTC\""
      }
      ...
    }

Datetime Schema via API

When Datetime data is returned via API calls, the schema for this information is returned as a three-element array. The additional elements to the specific are required to account for formatting options of for Datetime values.

Tip

Tip: Schema information for data types is primarily available via API calls. You may find schema information for columns in JSON versions of the visual profile and flow definitions when they are exported.


Example:

Code Block
"end_date": [
            "Datetime",
            "mm-dd-yy",
            "mm*dd*yyyy"
        ]
Array ElementDescriptionExample 1Example 2
Data typeThe internal name for the data type. For Datetime columns, this schema value should always be Datetime."Datetime""Datetime"
Sub-formatThe general format category of the data type"mm-dd-yy""mm-dd-yy"
Format typeThe specific formatting for the data type"mm*dd*yyyy""shortMonth*dd*yy"

D s also
labeldatetime