TIMESTAMPTZ data type

This topic describes the Firebolt implementation of the TIMESTAMPTZ data type.

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Overview

The TIMESTAMPTZ data type represents an absolute point in time as a date and time with microsecond resolution. Firebolt stores TIMESTAMPTZ values as Unix time, which is UTC without leap seconds.

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Difference between TIMESTAMPTZ and TIMESTAMP

With TIMESTAMP, the time zone is deliberately unspecified. For example, the start of the third millennium was celebrated on New Year’s Day at TIMESTAMP '2001-01-01 00:00:00', independent of the geographical location. However, that doesn’t mean that everybody in the world celebrated at the same absolute point in time. In Munich, Germany, the new year was celebrated at TIMESTAMPTZ '2001-01-01 00:00:00 Europe/Berlin', which was TIMESTAMPTZ '2000-12-31 23:00:00 UTC'. Seattle in the United States celebrated nine hours later at TIMESTAMPTZ '2001-01-01 00:00:00 US/Pacific', which was TIMESTAMPTZ '2001-01-01 08:00:00 UTC'.

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Literal string interpretation

TIMESTAMPTZ literals can be specified in one of three formats:

1. local_timestamp [time_zone]
2. local_timestamp[time_zone_offset]
3. local_timestamp[utc_time_zone]

• local_timestamp follows the ISO 8601 and RFC 3339 format: YYYY-[M]M-[D]D[( |T)[h]h:[m]m:[s]s[.f]].
  • YYYY: Four-digit year (0001 - 9999)
  • [M]M: One or two digit month (01 - 12)
  • [D]D: One or two digit day (01 - 31)
  • ( |T): A space or T separator
  • [h]h: One or two digit hour (00 - 23)
  • [m]m: One or two digit minutes (00 - 59)
  • [s]s: One or two digit seconds (00 - 59)
  • [.f]: Up to six digits after the decimal separator (000000 - 999999)
• time_zone is a string containing the name of the time zone.
• time_zone_offset is a string representing the offset from the UTC time zone.
  • Format: (+|-)H[H][:m[m]].
• utc_time_zone: The letter Z representing the UTC time zone.

Time zone names are from the tz database (see the list of tz database time zones). For times in the future, the latest known rule for the given time zone is applied. Firebolt does not support time zone abbreviations, as they cannot account for daylight savings time transitions, and some time zone abbreviations implied different UTC offsets at different times.

If a TIMESTAMPTZ literal has an explicit time zone specified, it is converted to Unix time using the appropriate offset. If not, Firebolt uses the session’s timezone setting and assumes the TIMESTAMPTZ literal is in that time zone. The default value of the timezone setting is UTC. To set it to, e.g., Europe/Berlin, you can issue: SET timezone = 'Europe/Berlin';. For more information, see system settings.

If only the date is specified, the time is assumed to be 00:00:00.000000.

Example

SET timezone = 'UTC';
SELECT TIMESTAMPTZ '1996-09-03 11:19:33.123456 Europe/Berlin';  --> 1996-09-03 09:19:33.123456+00
SELECT TIMESTAMPTZ '2023-1-29 6:3:42.7-3:30';  --> 2023-01-29 09:33:42.7+00

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Daylight savings time transitions

During a daylight savings time transition, a seemingly valid timestamp can represent a nonexistent or ambiguous timestamp. Firebolt resolves the problem by returning the later time point.

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”Spring forward” transitions

SET timezone = 'UTC';
SELECT TIMESTAMPTZ '2022-03-27 01:59:59 Europe/Berlin';  --> 2022-03-27 00:59:59+00
SELECT TIMESTAMPTZ '2022-03-27 02:00:00 Europe/Berlin';  --> 2022-03-27 01:00:00+00
SELECT TIMESTAMPTZ '2022-03-27 03:00:00 Europe/Berlin';  --> 2022-03-27 01:00:00+00

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”Fall back” transitions

SET timezone = 'UTC';
SELECT TIMESTAMPTZ '2022-10-30 01:59:59 Europe/Berlin';  --> 2022-10-29 23:59:59+00
SELECT TIMESTAMPTZ '2022-10-30 02:00:00 Europe/Berlin';  --> 2022-10-30 01:00:00+00
SELECT TIMESTAMPTZ '2022-10-30 03:00:00 Europe/Berlin';  --> 2022-10-30 02:00:00+00

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Functions and operators

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Type conversions

The TIMESTAMPTZ data type can be cast to and from types as follows:

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To TIMESTAMPTZ

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FROM TIMESTAMPTZ

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AT TIME ZONE

The dependence on the session’s timezone setting for type conversions can be problematic for implicit conversions. Therefore, we recommend using the AT TIME ZONE construct to be explicit about which time zone to use.

• TIMESTAMP AT TIME ZONE time_zone_str -> TIMESTAMPTZ
  Converts the given TIMESTAMP to TIMESTAMPTZ by interpreting it as local time in the time zone time_zone_str.

Example: SELECT TIMESTAMP '1996-09-03' at time zone 'Europe/Berlin' = TIMESTAMPTZ '1996-09-03 Europe/Berlin'; --> 1

• TIMESTAMPTZ AT TIME ZONE time_zone_str -> TIMESTAMP:
  Converts the given TIMESTAMPTZ to TIMESTAMP by transforming it from Unix time to local time in the time zone time_zone_str.

Example: SELECT TIMESTAMPTZ '1996-09-03 Europe/Berlin' AT TIME ZONE 'US/Pacific'; --> 1996-09-02 15:00:00

The AT TIME ZONE construct cannot be used with values of type DATE. However, you can explicitly cast a DATE value to TIMESTAMP and use the converted value instead.

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Comparison operators

A TIMESTAMPTZ value is also comparable with a DATE or TIMESTAMP value:

• The DATE value is converted to the TIMESTAMPTZ type for comparison with a TIMESTAMPTZ value.
• The TIMESTAMP value is converted to the TIMESTAMPTZ type for comparison with a TIMESTAMPTZ value.

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Arithmetic operators

TIMESTAMPTZ values can be used for arithmetic with intervals:

SET timezone = 'Europe/Berlin';
SELECT TIMESTAMPTZ '2022-10-30 Europe/Berlin' + interval '1 day';  --> 2022-10-31 00:00:00+01
SELECT TIMESTAMPTZ '2022-10-30 Europe/Berlin' + interval '24' hour;  --> 2022-10-30 23:00:00+01

SET timezone = 'US/Pacific';
SELECT TIMESTAMPTZ '2022-10-30 Europe/Berlin' + interval '1 day';  --> 2022-10-30 15:00:00-07
SELECT TIMESTAMPTZ '2022-10-30 Europe/Berlin' + interval '24' hour;  --> 2022-10-30 15:00:00-07

For more information, see Arithmetic with intervals.

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Serialization and deserialization

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Text, CSV, JSON

In the text, CSV, and JSON format, a TIMESTAMPTZ value is shown as local time after conversion from Unix time using the time zone specified in the session’s timezone setting. Time zone information using the session’s timezone setting is shown as a signed numeric offset from UTC (hh if it is an integral number of hours, hh:mm if it is an integral number of minutes, else hh:mm:ss), with a positive sign for zones east of Greenwich. The date and time components are output as a YYYY-MM-DD hh:mm:ss[.f] string. Firebolt outputs as few digits after the decimal separator as possible (at most six). Input is accepted in one of the literal formats described above.

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Parquet

TIMESTAMPTZ maps to Parquet’s 64-bit signed integer TIMESTAMP type with the parameter isAdjustedToUTC set to true and unit set to MICROS, representing the number of microseconds before or after 1970-01-01 00:00:00.000000 UTC. It’s also possible to import into a TIMESTAMPTZ column from Parquet’s 64-bit signed integer TIMESTAMP type with the parameter isAdjustedToUTC set to true and the unit set to MILLIS or NANOS. In this case, Firebolt implicitly extends or truncates to resolve in microseconds.

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Avro

TIMESTAMPTZ maps to Avro’s 64-bit signed integer timestamp-micros type, representing the number of microseconds before or after 1970-01-01 00:00:00.000000 UTC. It’s also possible to import into a TIMESTAMPTZ column from Avro’s timestamp-millis type.

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ORC

It’s not possible to import directly from ORC into a TIMESTAMPTZ column. ORC’s logical TIMESTAMP type is independent of a time zone and this would require a possibly unintended time zone conversion on import. Instead, first import using a TIMESTAMP column and then use the AT TIME ZONE expression to convert to TIMESTAMPTZ.