Timestamp Type
Timestamps represent points in absolute time, usually called instants.
DuckDB represents instants as the number of microseconds (µs) since 1970-01-01 00:00:00+00
.
Name | Aliases | Description |
---|---|---|
TIMESTAMP | datetime | time of day (ignores time zone) |
TIMESTAMP WITH TIME ZONE | TIMESTAMPTZ | time of day (uses time zone) |
A timestamp specifies a combination of DATE
(year, month, day) and a TIME
(hour, minute, second, millisecond). Timestamps can be created using the TIMESTAMP
keyword, where the data must be formatted according to the ISO 8601 format (YYYY-MM-DD hh:mm:ss[.zzzzzz][+-TT[:tt]]
).
-- 11:30 AM at 20 September, 1992 GMT
SELECT TIMESTAMP '1992-09-20 11:30:00';
-- 2:30 PM at 20 September, 1992 GMT
SELECT TIMESTAMP '1992-09-20 14:30:00';
Special Values
There are also three special date values that can be used on input:
Input String | Valid Types | Description |
---|---|---|
epoch | timestamp, timestamptz | 1970-01-01 00:00:00+00 (Unix system time zero) |
infinity | timestamp, timestamptz | later than all other time stamps |
-infinity | timestamp, timestamptz | earlier than all other time stamps |
The values infinity
and -infinity
are specially represented inside the system and will be displayed unchanged;
but epoch
is simply a notational shorthand that will be converted to the time stamp value when read.
SELECT '-infinity'::TIMESTAMP, 'epoch'::TIMESTAMP, 'infinity'::TIMESTAMP;
Negative | Epoch | Positive |
---|---|---|
-infinity | 1970-01-01 00:00:00 | infinity |
Functions
See Timestamp Functions.
Time Zones
The TIMESTAMPTZ
type can be binned into calendar and clock bins using a suitable extension.
The built in ICU extension implements all the binning and arithmetic functions using the
International Components for Unicode time zone and calendar functions.
To set the time zone to use, first load the ICU extension. The ICU extension comes pre-bundled with several DuckDB clients (including Python, R, JDBC, and ODBC), so this step can be skipped in those cases. In other cases you might first need to install and load the ICU extension.
INSTALL icu;
LOAD icu;
Next, use the Set TimeZone
command:
Set TimeZone='America/Los_Angeles';
Time binning operations for TIMESTAMPTZ
will then be implemented using the given time zone.
A list of available time zones can be pulled from the pg_timezone_names()
table function:
SELECT
name,
abbrev,
utc_offset
FROM pg_timezone_names()
ORDER BY
name;
You can also find a reference table of available time zones here.
Calendars
The ICU extension also supports non-Gregorian calendars using the Set Calendar
command.
Note that the require icu
step is only required if the DuckDB client does not bundle the
ICU extension.
LOAD icu;
Set Calendar='japanese';
Time binning operations for TIMESTAMPTZ
will then be implemented using the given calendar.
In this example, the era
part will now report the Japanese imperial era number.
A list of available calendars can be pulled from the icu_calendar_names()
table function:
SELECT name FROM icu_calendar_names() ORDER BY 1;
Settings
The current value of the TimeZone
and Calendar
settings are determined by ICU when it starts up.
They can be looked from in the duckdb_settings()
table function:
SELECT * FROM duckdb_settings() WHERE name = 'TimeZone';
-- America/Los_Angeles
SELECT * FROM duckdb_settings() WHERE name = 'Calendar';
-- gregorian