Handling and display of dates¶
In Dataiku DSS, “dates” mean “an absolute point in time”, meaning something that is expressible as a date and time and timezone.
2001-01-20T16:00:00.000+0200, which refer to the same point in time
(14:00Z is 2pm UTC, and 16:00+0200 is 4pm UTC+2, so 2pm UTC too).
DSS only displays dates in UTC especially in charts If you use the format date processor with a proper ISO8601 format, it will temporarily show it as a different time zone, but as soon as you write it out or read it in a chart, it will be in UTC again.
If you use a formatter to format as
16:00+0200 and selects the output to be a string,
then the string value will be preserved but it’s not a date anymore.
See Managing dates for more information.
Handling of dates in SQL¶
A date column in SQL will optionally be read in DSS as a “DSS date”, i.e. an “absolute point in time”, aka a “timestamp with time zone” in SQL parlance. So when DSS reads “2020-02-14” from the SQL table, it has to map it to a time. For that, it assumes that it is corresponding to “midnight”, but which midnight? On a SQL dataset, there is an “assumed time zone” setting for this. If you select “Local” as “assumed time zone” in the settings of a recipe’s input SQL dataset, then DSS will consider that it is reading “2020-02-14 at midnight in Netherlands” (for example, if your local TZ on your server is Europe/Amsterdam). Which DSS then displays in UTC, so “2020-02-13T23:00:00Z”. If you want it to show “2020-02-14T00:00:00Z”, you must set the assumed time zone to UTC.