Date and time functions and operators
Timespan operators
| Operation | Description | Example |
|---|---|---|
| interval * double precision → interval | Multiplies an interval by a double. | real '6.1' * interval '1' second → 00:00:06.1 interval '1' second * real '6.1' → 00:00:06.1 |
| interval / double precision → interval | Divides an interval by a double. Error is thrown for division by zero. | interval '12 days' / 4.2 → 2 days 20:34:17.143 interval '14000' / int '14' → 00:16:40 |
| interval + interval → interval | Adds an interval to an interval. | interval '20' hour + interval '10' hour → 30:00:00 |
| interval - interval → interval | Subtracts an interval from an interval. | interval '20' hour - interval '10' hour → 10:00:00 |
| time + interval → time | Adds an interval to a time. | time '18:20:49' + interval '1 hour' → 19:20:49 |
| time - interval → time | Subtracts an interval from a time. | time '18:20:49' - interval '2 hours' → 16:20:49 |
| time - time → interval | Subtracts a time from a time. | time '18:20:49' - time '16:07:16' → 02:13:33 |
Offsetting operators
| Operation | Description | Example |
|---|---|---|
| timestamp + interval → timestamp | Adds an interval to a timestamp. | '2022-03-13 01:00:00'::timestamp + interval '24' hour → 2022-03-14 01:00:00 |
| timestamp - interval → timestamp | Subtracts an interval from a timestamp. | '2022-03-14 01:00:00'::timestamp - interval '24' hour → 2022-03-13 01:00:00 |
| timestamp - timestamp → interval | Subtracts a timestamp from a timestamp. | '2022-03-13 03:00:00'::timestamp - '2022-03-13 01:00:00' → 02:00:00 |
| date + int → date | Adds a number of days to a date. | date '2022-06-23' + 4 → 2022-06-27 4 + Date '2022-06-23' → 2022-06-27 |
| date - int → date | Subtracts a number of days from a date. | date '2022-06-23' - 4 → 2022-06-19 |
| date - date → int | Subtracts a date from a date. | date '2020-03-01' - '2020-02-01' → 29 |
| date + interval → timestamp | Adds an interval to a date. | date '2022-04-08' + interval '10 hour' → 2022-04-08 10:00:00 |
| date - interval → timestamp | Subtracts an interval from a date. | date '2022-04-08' - interval '10 hour' → 2022-04-07 14:00:00 |
| date + time → timestamp | Adds a time to a date. | date '2022-06-23' + time '19:24:00' → 2022-06-23 19:24:00 time '19:24:00' + date '2022-06-23' → 2022-06-23 19:24:00 |
Timestamp with time zone operators
| Operation | Description | Example |
|---|---|---|
| timestamp AT TIME ZONE time_zone → timestamptz timestamptz AT TIME ZONE time_zone → timestamp | Converts times from timestamp to timestamptz (i.e., timestamp with time zone) or timestamptz to timestamp. Invalid local time during daylight saving forward is not supported. Ambiguous local time during daylight saving backward is interpreted as after the transition. | '2021-12-31 16:00:00'::timestamp AT TIME ZONE 'us/pacific' → 2022-01-01 00:00:00+00:00 '2022-01-01 00:00:00Z'::timestamptz AT TIME ZONE 'us/pacific' → 2021-12-31 16:00:00 |
| timestamptz + interval → timestamptz | Adds a fixed interval to a timestamp with time zone. See note below. | '2022-03-13 01:00:00Z'::timestamp with time zone + interval '24' hour → 2022-03-14 01:00:00+00:00 |
| timestamptz - interval → timestamptz | Subtracts a fixed interval from a timestamp with time zone. See note below. | '2022-03-14 01:00:00Z'::timestamp with time zone - interval '24' hour → 2022-03-13 01:00:00+00:00 |
| timestamptz - timestamptz → interval | Subtracts a timestamp with time zone from a timestamp with time zone and converts 24-hour intervals into days. | '2023-07-30 13:22:00-05:00'::timestamptz - '2023-07-29 13:22:00-04:00'::timestamptz → 1 day 01:00:00 |
An interval can contain hour/minute/second (i.e., fixed length) but not year/month/day (i.e., variable length).
Date and time functions
current_timestamp
Returns the current date and time.
current_timestamp() → *timestamptz*
current_timestamp() → `2023-09-06 07:06:46.724+00:00`
date_part
Extracts the value of a date or timestamp.
date_part ( precision_string, date/time_value[, time_zone ] ) → double_precision
precision_string can be year, month, day, hour, minute, second, doy, dow, millisecond, microsecond, epoch, millennium, century, decade, isoyear, quarter, week, isodow, or julian.
date/time_value can be a date, timestamp, time, timestamptz, or interval.
If date/time_value is timestamptz, it is recommended that time_zone is also specified, otherwise time_zone will default to the session time zone.
As date_part() returns values of type double precision, this can result in a loss of precision; therefore, using extract() is recommended.
date_part('day', date '2022-04-07') → 7
date_part('hour', timestamp '2022-04-07 22:00:30') → 22
date_part('second', time '22:00:30.123') → 30.123
date_part('day', interval '2 days') → 2
date_part('day', '2023-06-01 00:00:00Z'::timestamptz, 'Australia/Sydney') → 1
date_trunc
Truncates a date/time_value to a specified precision_string.
date_trunc ( precision_string, date/time_value[, time_zone ] ) → date/time_value
precision_string can be microseconds, milliseconds, second, minute, hour, day, week, month, quarter, year, decade, century, or millennium.
date/time_value can be timestamp, timestamptz (i.e., timestamp with time zone), or interval.
If date/time_value is timestamptz, it is recommended that time_zone is also specified, otherwise time_zone will default to the session time zone.
precision_string value 'week' is not supported for interval.
date_trunc('hour', timestamp '2202-02-16 20:38:40.123456') → 2202-02-16 20:00:00
date_trunc('day', timestamp with time zone '2202-02-16 20:38:40.123456Z', 'Australia/Sydney') → 2202-02-16 13:00:00+00:00
date_trunc('month', interval '2333 year 4 months 5 days 02:47:33.123') → 2333 years 4 mons
extract
This function has two variants.
extract ( field from source )
Extracts the value of a date or timestamp.
extract ( field from source [AT TIME ZONE time_zone]) → numeric
field can be year, month, day, hour, minute, second, doy, dow, millisecond, microsecond, epoch, millennium, century, decade, isoyear, quarter, week, isodow, or julian.
source can be the date, timestamp, timestamptz, time, or interval.
If time_zone is specified, source should be of type timestamptz.
extract(day from date '2022-04-07') → 7
extract(hour from timestamp '2022-04-07 22:00:30') → 22
extract(second from time '22:00:30.123') → 30.123000
extract(day from interval '2 days') → 2
extract(day from '2023-06-01 00:00:00Z'::timestamptz at time zone 'us/pacific') → 31
extract( epoch )
Converts the value of timestamp with time zone to Unix epoch seconds (the number of seconds since 1970-01-01 00:00:00 UTC). Negative for timestamps prior to that.
extract ( epoch FROM timestamp_with_time_zone ) → seconds_numeric
extract(epoch from '2010-01-01 12:34:56.789012Z'::timestamp with time zone) → 1262349296.789012
now
Returns the current date and time. For streaming queries, now() can only be used with WHERE, HAVING, and ON clauses. For more information, see Temporal filters. This constraint does not apply to batch queries.
now() → timestamptz
now() → '2023-08-04 21:29:59.662+00:00'
proctime
Returns the system time with time zone when a record is processed. You can use this function to specify the processing time of a record in a table or source.
proctime() → timestamptz
CREATE TABLE t1 (v1 int, proc_time timestamptz as proctime());
to_char
Converts the input to string according to the given format. Both uppercase and lowercase formats are supported.
to_char ( timestamptz, format ) → *string*
to_char ( timestamp, format ) → *string*
to_char(timestamp '2002-04-20 17:31:12.66', 'HH12:MI:SS') → '05:31:12'
to_char('2023-07-11 20:01:00-07:00'::timestamptz, 'HH12:MI:SS TZH:TZM') → 03:01:00 +00:00
to_date
Converts a string to a date according to the given format.
to_date ( date_string, format ) → date
to_date('05 Dec 2000', 'DD Mon YYYY') → '2000-12-05'
to_timestamp
This function has two variants.
to_timestamp ( seconds_double_precision )
Converts Unix epoch seconds (the number of seconds since 1970-01-01 00:00:00+00) to timestamptz.
to_timestamp ( seconds_double_precision ) → timestamptz
to_timestamp(1262349296.7890123) → '2010-01-01 12:34:56.789012+00:00'
to_timestamp ( string, timestamp_format )
Converts a string to timestamptz according to the given format.
to_timestamp ( string, timestamp_format ) → timestamptz
to_timestamp('2022 12 25', 'YYYY MM DD') → '2022-12-25 00:00:00+00:00'
to_timestamp('2022-12-25 00:00:00.900006', 'YYYY-MM-DD HH24:MI:SS.US') → '2022-12-25 00:00:00.900006+00:00'
to_timestamp('2022-12-25 00:00:00.906', 'YYYY-MM-DD HH24:MI:SS.MS') → '2022-12-25 00:00:00.906+00:00'
to_timestamp('2023-07-11 20:01:00-07:00', 'YYYY-MM-DD HH24:MI:SSTZH:TZM') → '2023-07-12 03:01:00+00:00'
Template patterns for date / time formatting
For date and time formatting functions like to_char, to_timestamp, and to_date, the format needs to be specified by using the supported template patterns. Any text that is not a template pattern is simply copied verbatim.
Please see the table below for the template patterns supported in RisingWave.
| Pattern | Description |
|---|---|
HH24 or hh24 | hour of day (00–23) |
HH12 or hh12 | hour of day (01–12) |
HH or hh | hour of day (01–12) |
AM, PM | meridiem indicator (without periods) |
am, pm | meridiem indicator (without periods) |
MI or mi | minute (00–59) |
SS or ss | second (00–59) |
YYYY or yyyy | year (4 or more digits) |
YY or yy | last 2 digits of year |
IYYY or iyyy | ISO 8601 week-numbering year (4 or more digits) |
IY or iy | last 2 digits of ISO 8601 week-numbering year |
MM or mm | month number (01–12) |
Month | full capitalized month name (blank-padded to 9 chars) |
Mon | abbreviated capitalized month name (3 chars in English) |
DD or dd | day of month (01–31) |
US or us | microsecond (000000–999999) |
MS or ms | millisecond (000–999) |
TZH:TZM or tzh:tzm | time-zone hours and minutes |
TZHTZM or tzhtzm | time-zone hours and minutes |
TZH or tzh | Time-zone hours. This pattern works only in to_timestamp. |
Delaying execution functions
The following functions are available to delay execution of the current session's process.
pg_sleep
The pg_sleep() function makes the current session's process sleep until the given number of seconds have elapsed. Fractional-second delays can be specified.
pg_sleep ( double precision )
SELECT pg_sleep(1.5);
pg_sleep_for
pg_sleep_for is a convenience function to allow the sleep time to be specified as an interval.
pg_sleep_for ( interval )
SELECT pg_sleep_for('5 minutes');
