Timezones in Malloy

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NOTE: While full timezone support exists in the calculation component of Malloy, the support in the rendering components is not yet present. It is best to avoid the use of the timezone: keyword at this time.

A timestamp represents a moment in time which does not change, however we often describe the moments in time relative to a timezone.

Without any timezone specification, all timestamps in Malloy are described as being in the "UTC" or zero-offset timezone.

A source or a query can specify a timezone with a locale name. When that is specified, the Malloy description of a timestamp which you would access through truncation or extraction, chnages.

   timezone: 'America/Mexico_City'

Literals

Timestamp literals without a timezone are assumed to be in the active timezone

query: showMe is emptySource -> {
  select: showMeVal is
    hours(
      @2021-01-01 00:00
      to
      @2021-01-01 00:00:00 [UTC]
    )
}

Without a timezone specification, showMeVal will be 0. Change it to

query: showMe is emptySource -> {
  timezone: 'America/Mexico_City'
  select: showMeVal is
    hours(
      @2021-01-01 00:00
      to
      @2021-01-01 00:00:00 [UTC]
    )
}

the result will be 6 (the difference in hours between UTC and Mexico City time, on that date)

Extraction / Truncation

With a timezone active, extraction and truncation happen at the moment of that timestamp, in the current timezone.

query: showMe is emptySouce -> {
  select: year(@2021-01-01 00:00 [UTC])
}

will return 2021 but

query: showMe is emptySouce -> {
  timezone: 'America/Mexico_City'
  select: year(@2021-01-01 00:00 [UTC])
}

will return 2020, because at that UTC midnight moment, it is still 2020 in Mexico City.