TIME_BUCKET (datetime)

Syntax

Description of the illustration time_bucket.gif

timebucket_optional_clause::=

Description of the illustration timebucket_optional_clause.gif

Purpose

Use TIME_BUCKET(datetime) to obtain the datetime over an interval that you specify.

TIME_BUCKET has three required arguments, and two optional arguments .

• The first argument datetime is the input to the bucket.

  The third argument origin is an anchor to which all buckets are aligned.

  datetime and origin can be DATE, TIMESTAMP, TIMESTAMP WITH TIMEZONE, TIMESTAMP WITH LOCAL TIMEZONE, EPOCH TIME, BINARY_FLOAT, BINARY_DOUBLE, CHAR, expression, or a bind variable.

  EPOCH TIME is represented by Oracle type NUMBER, which is the number of seconds that have elapsed since 00:00:00 UTC on 1 January 1970. The supported EPOCH TIME range is from SB8MINVAL(- 9223372036854775808, inclusive) to SB8MAXVAL(9223372036854775807, inclusive).

  There are implicit conversions for datetime and origin:

  • If it is BINARY_FLOAT or BINARY_DOUBLE, it will be converted to NUMBER implicitly. Note that you must account for the loss in precision from implicit conversions.

  • If it is CHAR, it will be converted to TIMESTAMP implicitly. Note that CHAR should match the session NLS_TIMESTAMP_FORMAT. Otherwise an error is raised.

  Fractional second is supported only if datetime and origin are EPOCH TIME, BINARY_FLOAT or BINARY_DOUBLE.

  The valid range for datetime and origin is from -4712-01-01 00:00:00 inclusive to 9999-12-31 23:59:59:00 inclusive.

• The second argument stride is a positive Oracle INTERVAL, ISO 8601 time interval string, expression or bind variable. Fractional second is supported only if datetime and origin are EPOCH TIME, BINARY_FLOAT or BINARY_DOUBLE.

  Oracle INTERVAL has two types of valid intervals: INTERVAL YEAR TO MONTH and INTERVAL DAY TO SECOND. If year or month is specified, all other units are ignored, if specified.

  For the ISO 8601 time interval string, years, months, days, hours, minutes and seconds are integers between 0 and 999999999. frac_secs is the fractional part of seconds between .0 and .999999999.

  The ISO 8601 time interval string that you specify should match the definition of Oracle INTERVAL. P is required, and no blanks are allowed in the value. If you specify T, then you must specify at least one of hours, minutes, or seconds. hours are based on 24-hour time.

  For example, P100DT05H indicates 100 days and 5 hours. P1Y2M‘indicates 1 year and 2 months. P1M1DT5H30M30S is equivalent to P1M which indicates 1 month.

  The syntax of the ISO 8601 time interval string:

  

  Description of the illustration iso_8601_time_interval_string.png

  Use only postive values for stride. (Although the Oracle INTERVAL and ISO 8601 time interval string can be positive or negative.)

  If datetime or origin is EPOCH TIME, BINARY_FLOAT or BINARY_DOUBLE, then stride cannot contain YEAR or MONTH. This is because month is variable and could be one of 28, 29, 30 or 31.

• The fourth argument is optional and specifies whether the start or the end of the time bucket is returned. Specify START to return the start value of the time bucket or END to return the end value . The values are case-insensitive. The default value is START.

• The fifth argument is optional and controls how the buckets (strides) are determined.

  ON OVERFLOW ROUND (default): The buckets will be cut on the same day as origin in the corresponding month. For a month that does not have that day, the bucket is rounded to the last day of the month.

  ON OVERFLOW ERROR: The buckets will be cut on the same day as origin in the corresponding month. For a month that does not have that day will error out.

  LAST DAY OF MONTH: If origin is the last day of the month and stride only contains MONTH and/or YEAR , the buckets will be cut on the corresponding last day of the month.

  For example, if origin is '1991-11-30' and stride is 'P1M', then:

  • For ON OVERFLOW ROUND, the start of each bucket will be:

    ..., 1991-11-30, 1991-12-30, 1992-01-30, 1992-02-29, 1992-03-30, 1992-04-30,...

  • For ON OVERFLOW ERROR, the start of each bucket will be:

    ..., 1991-11-30, 1991-12-30, 1992-01-30, error (or 1992-02-30), 1992-03-30, 1992-04-30,...

  • For LAST DAY OF MONTH, the start of each bucket will be:

    ..., 1991-11-30, 1991-12-31, 1992-01-31, 1992-02-29, 1992-03-31, 1992-04-30, ...

Rules

• The end of each bucket is the same as the beginning of the following bucket. For example, if the bucket is 2 years and the start of the slice is 2000-01-01, then the end of the bucket will be 2002-01- 01, not 2001-12-31. In other words, the bucket contains datetime greater than or equal to the start and less than (but not equal to) the end.

• In general, START of a bucket is always less than END of the bucket. But for the bucket on the two sides of the valid time range, START can be equal to END.

• origin and datetime can be positive or negative as long as it is in the valid range. Errors are raised if origin or datetime is outside of the valid range, or if the return value is outside of the valid range.

• If the input value is of type TIMESTAMP WITH TIME ZONE or TIMESTAMP WITH LOCAL TIME ZONE, then a time bucket might cross the daylight saving time boundaries. In this case, the duration of the time bucket is still the same as any other time bucket.

• If origin and datetime are TIMESTAMP WITH TIME ZONE or TIMESTAMP WITH LOCAL TIME ZONE, all arithmetic calculations are based in UTC time.

For details on dependencies with NLS_LANGUAGE and NLS_CALENDAR see Database Globalization Support Guide

Examples

The following examples use the NLS_DATE_FORMAT YYYY-MM-DD. Set the date format with ALTER SESSION:

ALTER SESSION SET NLS_DATE_FORMAT='YYYY-MM-DD';

Example 1

SELECT TIME_BUCKET (DATE '2022-06-29', INTERVAL '5' YEAR, DATE '2000-01-01', START);

The result is:

2020-01-01

The 5-year time bucket that contains 2022-06-29 is from 2020-01-01(start) to 2025- 01-01(end). The fourth argument START is used, so the start of the time bucket 2020-01-01 is returned.

Example 2

The following two queries are equivalent:

SELECT TIME_BUCKET ( DATE '-2022-06-29', 'P5M', DATE '-2022-01-01', END );

Or:

SELECT TIME_BUCKET ( DATE '-2022-06-29', INTERVAL '5' MONTH, DATE '-2022-01-01', END);

The result is:

-2022-11-01

The 5-month time bucket that contains -2022-06-29 is from 2022-06-01(start) to -2022- 11-01(end). The fourth argument END is used, so the end of the time bucket 2022-11-01 is returned.

Example 3

SELECT TIME_BUCKET ( DATE '2005-03-10', 'P1Y', DATE '2004-02-29' ON OVERFLOW ERROR );

The result is:

ORA-01839: date not valid for month specified

The one-year time bucket that contains '2005-03-10' is from error (or '2005-02-29') (start) to error (or '2006-02-29') (end). Default fourth argument START is used, so the start of the time bucket should be returned which is an error.

Example 4

SELECT TIME_BUCKET ( DATE '2005-03-10', 'P1Y', DATE '2004-02-29' ON OVERFLOW ROUND );

The result is:

2005-02-28

The one-year time bucket that contains '2005-03-10' is from '2005-02-28'(start) to '2006- 02-28'(end) since February 29 is rounded to February 28. Default fourth argument START is used, so the start of the time bucket is returned: '2005-02-28'.

Example 5

SELECT TIME_BUCKET ( DATE '2004-04-02', 'P1Y', DATE '2003-02-28' LAST DAY OF MONTH );

The result is:

2004-02-29

The one-year time bucket that contains '2003-02-28' is from '2004-02-29'(start) to '2005- 02-28'(end) since '2004-02-28' is rounded to the last day of that month which is '2004-02-29'. Default fourth argument START is used, so the start of the time bucket is returned: '2004-02- 29'.