Timestamp With Time Zone Functions

Version 0.6.1

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This section describes functions and operators for examining and manipulating TIMESTAMP WITH TIME ZONE values.

Despite the name, these values do not store a time zone - just an instant like TIMESTAMP. Instead, they request that the instant be binned and formatted using the current time zone.

Time zone support is not built in but can be provided by an extension, such as the ICU extension that ships with DuckDB.

In the examples below, the current time zone is presumed to be America/Los_Angeles using the Gregorian calendar.

Built-in Timestamp With Time Zone Functions

The table below shows the available scalar functions for TIMESTAMP WITH TIME ZONE values. Since these functions do not involve binning or display, they are always available.

Function	Description	Example	Result
`current_timestamp`	Current date and time (start of current transaction)	`current_timestamp`	`2022-10-08 12:44:46.122-07`
`get_current_timestamp()`	Current date and time (start of current transaction)	`get_current_timestamp()`	`2022-10-08 12:44:46.122-07`
`greatest(``timestamptz``,` `timestamptz``)`	The later of two timestamps	`greatest(TIMESTAMPTZ '1992-09-20 20:38:48', TIMESTAMPTZ '1992-03-22 01:02:03.1234')`	`1992-09-20 20:38:48-07`
`isfinite(``timestamptz``)`	Returns true if the timestamp with time zone is finite, false otherwise	`isfinite(TIMESTAMPTZ '1992-03-07')`	true
`isinf(``timestamptz``)`	Returns true if the timestamp with time zone is infinite, false otherwise	`isinf(TIMESTAMPTZ '-infinity')`	true
`least(``timestamptz``,` `timestamptz``)`	The earlier of two timestamps	`least(TIMESTAMPTZ '1992-09-20 20:38:48', TIMESTAMPTZ '1992-03-22 01:02:03.1234')`	`1992-03-22 01:02:03.1234-08`
`now()`	Current date and time (start of current transaction)	`now()`	`2022-10-08 12:44:46.122-07`
`transaction_timestamp()`	Current date and time (start of current transaction)	`transaction_timestamp()`	`2022-10-08 12:44:46.122-07`

Timestamp With Time Zone Strings

With no time zone extension loaded, TIMESTAMPTZ values will be cast to and from strings using offset notation. This will let you specify an instant correctly without access to time zone information. Without a time zone extension, TIMESTAMPTZ values will be displayed using GMT offsets:

select '2022-10-08 13:13:34-07'::TIMESTAMPTZ'
-- 2022-10-08 20:13:34+00

If a time zone extension such as ICU is loaded, then a time zone can be parsed from a string and cast to a representation in the local time zone:

select '2022-10-08 13:13:34 Europe/Amsterdam'::TIMESTAMPTZ::VARCHAR;
-- 2022-10-08 04:13:34-07

ICU Timestamp With Time Zone Operators

The table below shows the available mathematical operators for TIMESTAMP WITH TIME ZONE values provided by the ICU extension.

Operator	Description	Example	Result
`+`	addition of an `INTERVAL`	`TIMESTAMPTZ '1992-03-22 01:02:03' + INTERVAL 5 DAY`	`1992-03-27 01:02:03`
`-`	subtraction of `TIMESTAMPTZ`s	`TIMESTAMPTZ '1992-03-27' - TIMESTAMPTZ '1992-03-22'`	`5 days`
`-`	subtraction of an `INTERVAL`	`TIMESTAMPTZ '1992-03-27 01:02:03' - INTERVAL 5 DAY`	`1992-03-22 01:02:03`

Adding to or subtracting from infinite values produces the same infinite value.

ICU Timestamp With Time Zone Functions

The table below shows the ICU provided scalar functions for TIMESTAMP WITH TIME ZONE values.

Function	Description	Example	Result
`age(``timestamptz``,` `timestamptz``)`	Subtract arguments, resulting in the time difference between the two timestamps	`age(TIMESTAMP '2001-04-10', TIMESTAMP '1992-09-20')`	`8 years 6 months 20 days`
`age(``timestamptz``)`	Subtract from current_date	`age(TIMESTAMP '1992-09-20')`	`29 years 1 month 27 days 12:39:00.844`
`date_diff(``part``,` `startdate``,` `enddate``)`	The number of partition boundaries between the timestamps	`date_diff('hour', TIMESTAMPTZ '1992-09-30 23:59:59', TIMESTAMPTZ '1992-10-01 01:58:00')`	`2`
`date_part(``part``,` `timestamptz``)`	Get subfield (equivalent to extract)	`date_part('minute', TIMESTAMPTZ '1992-09-20 20:38:40')`	`38`
`date_part([``part``, ...],` `timestamptz``)`	Get the listed subfields as a `struct`. The list must be constant.	`date_part(['year', 'month', 'day'], TIMESTAMPTZ '1992-09-20 20:38:40-07')`	`{year: 1992, month: 9, day: 20}`
`date_sub(``part``,` `startdate``,` `enddate``)`	The number of complete partitions between the timestamps	`date_sub('hour', TIMESTAMPTZ '1992-09-30 23:59:59', TIMESTAMPTZ '1992-10-01 01:58:00')`	`1`
`date_trunc(``part``,` `timestamptz``)`	Truncate to specified precision	`date_trunc('hour', TIMESTAMPTZ '1992-09-20 20:38:40')`	`1992-09-20 20:00:00`
`extract(``field` `from` `timestamptz``)`	Get subfield from a timestamp with time zone	`extract('hour' FROM TIMESTAMPTZ '1992-09-20 20:38:48')`	`20`
`last_day(``timestamptz``)`	The last day of the month.	`last_day(TIMESTAMPTZ '1992-03-22 01:02:03.1234')`	`1992-03-31`
`make_timestamptz(``bigint``,` `bigint``,` `bigint``,` `bigint``,` `bigint``,` `double``)`	The timestamp with time zone for the given parts in the current time zone	`make_timestamptz(1992, 9, 20, 13, 34, 27.123456)`	`1992-09-20 13:34:27.123456-07`
`make_timestamptz(``bigint``,` `bigint``,` `bigint``,` `bigint``,` `bigint``,` `double``,` `string``)`	The timestamp with time zone for the given parts and time zone	`make_timestamptz(1992, 9, 20, 15, 34, 27.123456, 'CET')`	`1992-09-20 05:34:27.123456-07`
`strftime(``timestamptz``,` `format``)`	Converts timestamp with time zone to string according to the format string	`strftime(timestamptz '1992-01-01 20:38:40', '%a, %-d %B %Y - %I:%M:%S %p')`	`Wed, 1 January 1992 - 08:38:40 PM`
`strptime(``text``,` `format``)`	Converts string to timestamp with time zone according to the format string if `%Z` is specified.	`strptime('Wed, 1 January 1992 - 08:38:40 PST', '%a, %-d %B %Y - %H:%M:%S %Z')`	`1992-01-01 08:38:40-08`
`timezone(``text``,` `timestamp``)`	Use the date parts of the timestamp to construct a timestamp in the given time zone. Effectively, the argument is a “local” time.	`timezone('America/Denver', TIMESTAMP '2001-02-16 20:38:40')`	`2001-02-15 19:38:40-08`
`timezone(``text``,` `timestamptz``)`	Use the date parts of the timestamp in the given time zone to construct a timestamp. Effectively, the result is a “local” time.	`timezone('America/Denver', TIMESTAMPTZ '2001-02-16 20:38:40-05')`	`2001-02-15 18:38:40`

There are also dedicated extraction functions to get the subfields.

Infinities

Functions applied to infinite dates will either return the same infinite dates (e.g, greatest) or NULL (e.g., date_part) depending on what “makes sense”. In general, if the function needs to examine the parts of the infinite temporal value, the result will be NULL.

At Time Zone

The AT TIME ZONE syntax is syntactic sugar for the (two argument) timezone function listed above:

timestamp '2001-02-16 20:38:40' AT TIME ZONE 'America/Denver'
-- 2001-02-16 19:38:40-08
timestamp with time zone '2001-02-16 20:38:40-05' AT TIME ZONE 'America/Denver'
-- 2001-02-16 18:38:40

These operations are intended to allow queries to work with “local” timestamps. A local timestamp is effectively a way of encoding the part values from a time zone into a single value. They should be used with caution because the produced values can contain gaps and ambiguities thanks to daylight savings time. Often the same functionality can be implemented more reliably using the struct variant of the date_part function.

Calendars

The ICU extension also supports non-Gregorian calendars. If such a calendar is current, then the display and binning operations will use that calendar.

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