A range aggregation that is dedicated for date values. The main difference between this aggregation and the normal <<search-aggregations-bucket-range-aggregation,range>> aggregation is that the `from` and `to` values can be expressed in Date Math expressions, and it is also possible to specify a date format by which the `from` and `to` response fields will be returned.
Note that this aggregration includes the `from` value and excludes the `to` value for each range.
All ASCII letters are reserved as format pattern letters, which are defined as follows:
[options="header"]
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|Symbol |Meaning |Presentation |Examples
|G |era |text |AD
|C |century of era (>=0) |number |20
|Y |year of era (>=0) |year |1996
|x |weekyear |year |1996
|w |week of weekyear |number |27
|e |day of week |number |2
|E |day of week |text |Tuesday; Tue
|y |year |year |1996
|D |day of year |number |189
|M |month of year |month |July; Jul; 07
|d |day of month |number |10
|a |halfday of day |text |PM
|K |hour of halfday (0~11) |number |0
|h |clockhour of halfday (1~12) |number |12
|H |hour of day (0~23) |number |0
|k |clockhour of day (1~24) |number |24
|m |minute of hour |number |30
|s |second of minute |number |55
|S |fraction of second |number |978
|z |time zone |text |Pacific Standard Time; PST
|Z |time zone offset/id |zone |-0800; -08:00; America/Los_Angeles
|' |escape for text |delimiter
|'' |single quote |literal |'
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The count of pattern letters determine the format.
Text:: If the number of pattern letters is 4 or more, the full form is used; otherwise a short or abbreviated form is used if available.
Number:: The minimum number of digits. Shorter numbers are zero-padded to this amount.
Year:: Numeric presentation for year and weekyear fields are handled specially. For example, if the count of 'y' is 2, the year will be displayed as the zero-based year of the century, which is two digits.
Month:: 3 or over, use text, otherwise use number.
Zone:: 'Z' outputs offset without a colon, 'ZZ' outputs the offset with a colon, 'ZZZ' or more outputs the zone id.
Zone names:: Time zone names ('z') cannot be parsed.
Any characters in the pattern that are not in the ranges of ['a'..'z'] and ['A'..'Z'] will be treated as quoted text. For instance, characters like ':', '.', ' ', '#' and '?' will appear in the resulting time text even they are not embraced within single quotes.