Temporal Types, Functions, and Operators​

A timezone-aware type representing a moment in time.

All dates must correspond to dates that exist in the proleptic Gregorian calendar.

Casting is a simple way to obtain a datetime value in an expression:

SELECT <datetime>'2018-05-07T15:01:22.306916+00';
SELECT <datetime>'2018-05-07T15:01:22+00';

Note that when casting from strings, the string should be in ISO 8601 format with timezone included:

db> 

SELECT <datetime>'January 01 2019 UTC';

InvalidValueError: invalid input syntax for type
std::datetime: 'January 01 2019 UTC'
Hint: Please use ISO8601 format. Alternatively "to_datetime"
function provides custom formatting options.

db> 

SELECT <datetime>'2019-01-01T15:01:22';

InvalidValueError: invalid input syntax for type
std::datetime: '2019-01-01T15:01:22'
Hint: Please use ISO8601 format. Alternatively "to_datetime"
function provides custom formatting options.

All datetime values are restricted to the range from year 1 to 9999.

See functions datetime_get(), to_datetime(), and to_str() for more ways of working with datetime.

A type representing date and time without time zone.

Casting is a simple way to obtain a cal::local_datetime value in an expression:

SELECT <cal::local_datetime>'2018-05-07T15:01:22.306916';
SELECT <cal::local_datetime>'2018-05-07T15:01:22';

Note that when casting from strings, the string should be in ISO 8601 format without timezone:

db> 

SELECT <cal::local_datetime>'2019-01-01T15:01:22+00';

InvalidValueError: invalid input syntax for type
cal::local_datetime: '2019-01-01T15:01:22+00'
Hint: Please use ISO8601 format. Alternatively
"cal::to_local_datetime" function provides custom formatting
options.

db> 

SELECT <cal::local_datetime>'January 01 2019';

InvalidValueError: invalid input syntax for type
cal::local_datetime: 'January 01 2019'
Hint: Please use ISO8601 format. Alternatively
"cal::to_local_datetime" function provides custom formatting
options.

All datetime values are restricted to the range from year 1 to 9999.

See functions datetime_get(), cal::to_local_datetime(), and to_str() for more ways of working with cal::local_datetime.

A type representing a date without a time zone.

Casting is a simple way to obtain a cal::local_date value in an expression:

SELECT <cal::local_date>'2018-05-07';

Note that when casting from strings, the string should be in ISO 8601 date format.

See functions cal::date_get(), cal::to_local_date(), and to_str() for more ways of working with cal::local_date.

A type representing time without a time zone.

Casting is a simple way to obtain a cal::local_time value in an expression:

SELECT <cal::local_time>'15:01:22.306916';
SELECT <cal::local_time>'15:01:22';

Note that when casting from strings, the string should be in ISO 8601 time format.

See functions cal::time_get(), cal::to_local_time(), and to_str() for more ways of working with cal::local_time.

A type representing a span of time.

Valid units when converting from a string (and combinations of them): - 'microseconds' - 'milliseconds' - 'seconds' - 'minutes' - 'hours'

SELECT <duration>'45.6 seconds';
SELECT <duration>'15 milliseconds';
SELECT <duration>'48 hours 45 minutes';
SELECT <duration>'-7 minutes';

All date/time types support the + and - arithmetic operations with durations:

db> 

select <datetime>'2019-01-01T00:00:00Z' - <duration>'24 hours';

{<datetime>'2018-12-31T00:00:00+00:00'}

db> 

select <cal::local_time>'22:00' + <duration>'1 hour';

{<cal::local_time>'23:00:00'}

Duration is a fixed number of seconds and microseconds and isn’t adjusted by timezone, length of month or anything else in datetime calculations.

See functions to_duration(), and to_str() and date/time operators for more ways of working with duration.

A type representing a span of time.

Unlike std::duration a relative_duration is not a precise measurment because it uses 3 different units under the hood: months, days and seconds. However not all months have the same number of days and not all days have the same number of seconds. For example 2019 was a leap year and had 366 days. Notice how the number of hours in each year below is different.

db> 
... 
... 
... 
... 

WITH
    first_day_of_2020 := <datetime>'2020-01-01T00:00:00Z',
    one_year := <cal::relative_duration>'1 year',
    first_day_of_next_year := first_day_of_2020 + one_year
SELECT first_day_of_next_year - first_day_of_2020;

{<duration>'8784:00:00'}

db> 
... 
... 
... 
... 

WITH
    first_day_of_2019 := <datetime>'2019-01-01T00:00:00Z',
    one_year := <cal::relative_duration>'1 year',
    first_day_of_next_year := first_day_of_2019 + one_year
SELECT first_day_of_next_year - first_day_of_2019;

{<duration>'8760:00:00'}

Valid units when converting from a string (and combinations of them): - 'microseconds' - 'milliseconds' - 'seconds' - 'minutes' - 'hours' - 'days' - 'weeks' - 'months' - 'years' - 'decades' - 'centuries' - 'millennia'

SELECT <cal::relative_duration>'45.6 seconds';
SELECT <cal::relative_duration>'15 milliseconds';
SELECT <cal::relative_duration>'3 weeks 45 minutes';
SELECT <cal::relative_duration>'-7 millennia';

All date/time types support the + and - arithmetic operations with relative_durations:

db> 
... 

select <datetime>'2019-01-01T00:00:00Z' -
       <cal::relative_duration>'3 years';

{<datetime>'2016-01-01T00:00:00+00:00'}

db> 
... 

select <cal::local_time>'22:00' +
       <cal::relative_duration>'1 hour';

{<cal::local_time>'23:00:00'}

If an arithmetic operation results in a day that doesn’t exist in the given month, the last day of the month is used instead.

db> 
... 

select <cal::local_datetime>"2021-01-31T15:00:00" +
       <cal::relative_duration>"1 month";

{<cal::local_datetime>'2021-02-28T15:00:00'}

During arithmetic operations involving a relative_duration consisting of multiple components (units), higher-order components are applied first, followed by lower-order elements.

db> 
... 

select <cal::local_datetime>"2021-04-30T15:00:00" +
       <cal::relative_duration>"1 month 1 day";

{<cal::local_datetime>'2021-05-31T15:00:00'}

Compare this to adding up the same duration components separately with higher-order units first and then lower-order, which produces the same result as above:

db> 
... 
... 

select <cal::local_datetime>"2021-04-30T15:00:00" +
       <cal::relative_duration>"1 month" +
       <cal::relative_duration>"1 day";

{<cal::local_datetime>'2021-05-31T15:00:00'}

When the order is reversed the result may actually be different for some corner cases:

db> 
... 
... 

select <cal::local_datetime>"2021-04-30T15:00:00" +
       <cal::relative_duration>"1 day" +
       <cal::relative_duration>"1 month";

{<cal::local_datetime>'2021-06-01T15:00:00'}

Gotchas

Due to the implementation of relative_duration logic, arithmetic operations may behave counterintuitively.

Non-associative

db> 
... 
... 

select <cal::local_datetime>'2021-01-31T00:00:00' +
       <cal::relative_duration>'1 month' +
       <cal::relative_duration>'1 month';

{<cal::local_datetime>'2021-03-28T00:00:00'}

db> 
... 
... 

select <cal::local_datetime>'2021-01-31T00:00:00' +
      (<cal::relative_duration>'1 month' +
       <cal::relative_duration>'1 month');

{<cal::local_datetime>'2021-03-31T00:00:00'}

db> 
... 
... 

select <cal::local_date>'2021-01-31' +
       <cal::relative_duration>'12 hours' +
       <cal::relative_duration>'12 hours';

{<cal::local_date>'2021-01-31'}

db> 
... 
... 

select <cal::local_date>'2021-01-31' +
      (<cal::relative_duration>'12 hours' +
       <cal::relative_duration>'12 hours');

{<cal::local_date>'2021-02-01'}

Lossy

db> 
... 
... 
... 

with m := <cal::relative_duration>'1 month'
select <cal::local_date>'2021-01-31' + m
       =
       <cal::local_date>'2021-01-30' + m;

{true}

Asymmetric

db> 
... 

with m := <cal::relative_duration>'1 month'
select <cal::local_date>'2021-01-31' + m - m;

{<cal::local_date>'2021-01-28'}

Non-monotonic

db> 
... 
... 
... 

with m := <cal::relative_duration>'1 month'
select <cal::local_datetime>'2021-01-31T01:00:00' + m
       <
       <cal::local_datetime>'2021-01-30T23:00:00' + m;

{true}

db> 
... 
... 
... 

with m := <cal::relative_duration>'2 month'
select <cal::local_datetime>'2021-01-31T01:00:00' + m
       <
       <cal::local_datetime>'2021-01-30T23:00:00' + m;

{false}

See functions cal::to_relative_duration(), and to_str() and date/time operators for more ways of working with cal::relative_duration.

Time interval addition.

This operator is commutative.

db> 

SELECT <cal::local_time>'22:00' + <duration>'1 hour';

{<cal::local_time>'23:00:00'}

db> 

SELECT <duration>'1 hour' + <cal::local_time>'22:00';

{<cal::local_time>'23:00:00'}

db> 

SELECT <duration>'1 hour' + <duration>'2 hours';

{10800s}

Time interval and date/time subtraction.

db> 
... 

SELECT <datetime>'2019-01-01T01:02:03+00' -
  <duration>'24 hours';

{<datetime>'2018-12-31T01:02:03Z'}

db> 
... 

SELECT <datetime>'2019-01-01T01:02:03+00' -
  <datetime>'2019-02-01T01:02:03+00';

{-2678400s}

db> 
... 

SELECT <duration>'1 hour' -
  <duration>'2 hours';

{-3600s}

It is an error to subtract a date/time object from a time interval:

db> 
... 

SELECT <duration>'1 day' -
  <datetime>'2019-01-01T01:02:03+00';

QueryError: operator '-' cannot be applied to operands ...

It is also an error to subtract timezone-aware std::datetime to or from cal::local_datetime:

db> 
... 

SELECT <datetime>'2019-01-01T01:02:03+00' -
  <cal::local_datetime>'2019-02-01T01:02:03';

QueryError: operator '-' cannot be applied to operands ...

Return the current server date and time.

db> 

SELECT datetime_current();

{<datetime>'2018-05-14T20:07:11.755827Z'}

Return the date and time of the start of the current transaction.

Return the date and time of the start of the current statement.

Extract a specific element of input datetime by name.

The datetime scalar has the following elements available for extraction:

• 'epochseconds' - the number of seconds since 1970-01-01 00:00:00 UTC (Unix epoch) for datetime or local time for cal::local_datetime. It can be negative.

• 'century' - the century according to the Gregorian calendar

• 'day' - the day of the month (1-31)

• 'decade' - the decade (year divided by 10 and rounded down)

• 'dow' - the day of the week from Sunday (0) to Saturday (6)

• 'doy' - the day of the year (1-366)

• 'hour' - the hour (0-23)

• 'isodow' - the ISO day of the week from Monday (1) to Sunday (7)

• 'isoyear' - the ISO 8601 week-numbering year that the date falls in. See the 'week' element for more details.

• 'microseconds' - the seconds including fractional value expressed as microseconds

• 'millennium' - the millennium. The third millennium started on Jan 1, 2001.

• 'milliseconds' - the seconds including fractional value expressed as milliseconds

• 'minutes' - the minutes (0-59)

• 'month' - the month of the year (1-12)

• 'quarter' - the quarter of the year (1-4)

• 'seconds' - the seconds, including fractional value from 0 up to and not including 60

• 'week' - the number of the ISO 8601 week-numbering week of the year. ISO weeks are defined to start on Mondays and the first week of a year must contain Jan 4 of that year.

• 'year' - the year

db> 
... 
... 

SELECT datetime_get(
    <datetime>'2018-05-07T15:01:22.306916+00',
    'epochseconds');

{1525705282.306916}

db> 
... 
... 

SELECT datetime_get(
    <datetime>'2018-05-07T15:01:22.306916+00',
    'year');

{2018}

db> 
... 
... 

SELECT datetime_get(
    <datetime>'2018-05-07T15:01:22.306916+00',
    'quarter');

{2}

db> 
... 
... 

SELECT datetime_get(
    <datetime>'2018-05-07T15:01:22.306916+00',
    'doy');

{127}

db> 
... 
... 

SELECT datetime_get(
    <datetime>'2018-05-07T15:01:22.306916+00',
    'hour');

{15}

Extract a specific element of input time by name.

The cal::local_time scalar has the following elements available for extraction:

• 'midnightseconds'

• 'hour'

• 'microseconds'

• 'milliseconds'

• 'minutes'

• 'seconds'

For full description of what these elements extract see datetime_get().

db> 
... 

SELECT cal::time_get(
    <cal::local_time>'15:01:22.306916', 'minutes');

{1}

db> 
... 

SELECT cal::time_get(
    <cal::local_time>'15:01:22.306916', 'milliseconds');

{22306.916}

Extract a specific element of input date by name.

The cal::local_date scalar has the following elements available for extraction:

• 'century' - the century according to the Gregorian calendar

• 'day' - the day of the month (1-31)

• 'decade' - the decade (year divided by 10 and rounded down)

• 'dow' - the day of the week from Sunday (0) to Saturday (6)

• 'doy' - the day of the year (1-366)

• 'isodow' - the ISO day of the week from Monday (1) to Sunday (7)

• 'isoyear' - the ISO 8601 week-numbering year that the date falls in. See the 'week' element for more details.

• 'millennium' - the millennium. The third millennium started on Jan 1, 2001.

• 'month' - the month of the year (1-12)

• 'quarter' - the quarter of the year (1-4) not including 60

• 'week' - the number of the ISO 8601 week-numbering week of the year. ISO weeks are defined to start on Mondays and the first week of a year must contain Jan 4 of that year.

• 'year' - the year

db> 
... 

SELECT cal::date_get(
    <cal::local_date>'2018-05-07', 'century');

{21}

db> 
... 

SELECT cal::date_get(
    <cal::local_date>'2018-05-07', 'year');

{2018}

db> 
... 

SELECT cal::date_get(
    <cal::local_date>'2018-05-07', 'month');

{5}

db> 
... 

SELECT cal::date_get(
    <cal::local_date>'2018-05-07', 'doy');

{127}

Truncate the input datetime to a particular precision.

The valid unit values in order or decreasing precision are:

• 'microseconds'

• 'milliseconds'

• 'seconds'

• 'minutes'

• 'hours'

• 'days'

• 'weeks'

• 'months'

• 'quarters'

• 'years'

• 'decades'

• 'centuries'

db> 
... 

SELECT datetime_truncate(
    <datetime>'2018-05-07T15:01:22.306916+00', 'years');

{<datetime>'2018-01-01T00:00:00Z'}

db> 
... 

SELECT datetime_truncate(
    <datetime>'2018-05-07T15:01:22.306916+00', 'quarters');

{<datetime>'2018-04-01T00:00:00Z'}

db> 
... 

SELECT datetime_truncate(
    <datetime>'2018-05-07T15:01:22.306916+00', 'days');

{<datetime>'2018-05-07T00:00:00Z'}

db> 
... 

SELECT datetime_truncate(
    <datetime>'2018-05-07T15:01:22.306916+00', 'hours');

{<datetime>'2018-05-07T15:00:00Z'}

Truncate the input duration to a particular precision.

The valid unit values are: - 'microseconds' - 'milliseconds' - 'seconds' - 'minutes' - 'hours'

db> 
... 

SELECT duration_truncate(
    <duration>'15:01:22', 'hours');

{54000s}

db> 
... 

SELECT duration_truncate(
    <duration>'15:01:22.306916', 'minutes');

{54060s}

Create a datetime value.

The datetime value can be parsed from the input str s. By default, the input is expected to conform to ISO 8601 format. However, the optional argument fmt can be used to override the input format to other forms.

db> 

SELECT to_datetime('2018-05-07T15:01:22.306916+00');

{<datetime>'2018-05-07T15:01:22.306916Z'}

db> 

SELECT to_datetime('2018-05-07T15:01:22+00');

{<datetime>'2018-05-07T15:01:22Z'}

db> 
... 

SELECT to_datetime('May 7th, 2018 15:01:22 +00',
                   'Mon DDth, YYYY HH24:MI:SS TZH');

{<datetime>'2018-05-07T15:01:22Z'}

Alternatively, the datetime value can be constructed from a cal::local_datetime value:

db> 
... 

SELECT to_datetime(
  <cal::local_datetime>'2019-01-01T01:02:03', 'HKT');

{<datetime>'2018-12-31T17:02:03Z'}

Another way to construct a the datetime value is to specify it in terms of its component parts: year, month, day, hour, min, sec, and timezone

db> 
... 

SELECT to_datetime(
    2018, 5, 7, 15, 1, 22.306916, 'UTC');

{<datetime>'2018-05-07T15:01:22.306916000Z'}

Finally, it is also possible to convert a Unix timestamp to a datetime

db> 

SELECT to_datetime(1590595184.584);

{<datetime>'2020-05-27T15:59:44.584000000Z'}

Create a cal::local_datetime value.

Similar to to_datetime(), the cal::local_datetime value can be parsed from the input str s with an optional fmt argument or it can be given in terms of its component parts: year, month, day, hour, min, sec.

For more details on formatting see here.

db> 

SELECT cal::to_local_datetime('2018-05-07T15:01:22.306916');

{<cal::local_datetime>'2018-05-07T15:01:22.306916'}

db> 
... 

SELECT cal::to_local_datetime('May 7th, 2018 15:01:22',
                         'Mon DDth, YYYY HH24:MI:SS');

{<cal::local_datetime>'2018-05-07T15:01:22'}

db> 
... 

SELECT cal::to_local_datetime(
    2018, 5, 7, 15, 1, 22.306916);

{<cal::local_datetime>'2018-05-07T15:01:22.306916'}

A timezone-aware datetime type can be converted to local datetime in the specified timezone:

db> 
... 
... 

SELECT cal::to_local_datetime(
  <datetime>'2018-12-31T22:00:00+08',
  'US/Central');

{<cal::local_datetime>'2018-12-31T08:00:00'}

Create a cal::local_date value.

Similar to to_datetime(), the cal::local_date value can be parsed from the input str s with an optional fmt argument or it can be given in terms of its component parts: year, month, day.

For more details on formatting see here.

db> 

SELECT cal::to_local_date('2018-05-07');

{<cal::local_date>'2018-05-07'}

db> 

SELECT cal::to_local_date('May 7th, 2018', 'Mon DDth, YYYY');

{<cal::local_date>'2018-05-07'}

db> 

SELECT cal::to_local_date(2018, 5, 7);

{<cal::local_date>'2018-05-07'}

A timezone-aware datetime type can be converted to local date in the specified timezone:

db> 
... 
... 

SELECT cal::to_local_date(
  <datetime>'2018-12-31T22:00:00+08',
  'US/Central');

{<cal::local_date>'2019-01-01'}

Create a cal::local_time value.

Similar to to_datetime(), the cal::local_time value can be parsed from the input str s with an optional fmt argument or it can be given in terms of its component parts: hour, min, sec.

For more details on formatting see here.

db> 

SELECT cal::to_local_time('15:01:22.306916');

{<cal::local_time>'15:01:22.306916'}

db> 

SELECT cal::to_local_time('03:01:22pm', 'HH:MI:SSam');

{<cal::local_time>'15:01:22'}

db> 

SELECT cal::to_local_time(15, 1, 22.306916);

{<cal::local_time>'15:01:22.306916'}

A timezone-aware datetime type can be converted to local date in the specified timezone:

db> 
... 
... 

SELECT cal::to_local_time(
  <datetime>'2018-12-31T22:00:00+08',
  'US/Pacific');

{<cal::local_time>'06:00:00'}

Create a duration value.

This function uses NAMED ONLY arguments to create a duration value. The available duration fields are: hours, minutes, seconds, microseconds.

db> 
... 
... 

SELECT to_duration(hours := 1,
                   minutes := 20,
                   seconds := 45);

{4845s}

db> 

SELECT to_duration(seconds := 4845);

{4845s}

Return duration as total number of seconds in interval.

db> 

SELECT duration_to_seconds(<duration>'1 hour');

{3600.000000n}

db> 

SELECT duration_to_seconds(<duration>'10 second 123 ms');

{10.123000n}

Create a cal::relative_duration value.

This function uses NAMED ONLY arguments to create a cal::relative_duration value. The available duration fields are: years, months, days, hours, minutes, seconds, microseconds.

db> 

SELECT cal::to_relative_duration(years := 5, minutes := 1);

{P5YT1S}

db> 

SELECT cal::to_relative_duration(months := 3, days := 27);

{P3M27D}