55 lines
1.3 KiB
Plaintext
55 lines
1.3 KiB
Plaintext
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[role="xpack"]
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[testenv="basic"]
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[[sql-functions-grouping]]
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=== Grouping Functions
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beta[]
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Functions for creating special __grouping__s (also known as _bucketing_); as such these need to be used
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as part of the <<sql-syntax-group-by, grouping>>.
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[[sql-functions-grouping-histogram]]
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==== `HISTOGRAM`
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.Synopsis
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[source, sql]
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----
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HISTOGRAM ( numeric_exp<1>, numeric_interval<2>)
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HISTOGRAM ( date_exp<3>, date_time_interval<4>)
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----
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*Input*:
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<1> numeric expression (typically a field)
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<2> numeric interval
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<3> date/time expression (typically a field)
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<4> date/time <<sql-functions-datetime-interval, interval>>
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*Output*: non-empty buckets or groups of the given expression divided according to the given interval
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.Description
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The histogram function takes all matching values and divides them into buckets with fixed size matching the given interval, using (roughly) the following formula:
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[source, sql]
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----
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bucket_key = Math.floor(value / interval) * interval
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----
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`Histogram` can be applied on either numeric fields:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[histogramNumeric]
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----
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or date/time fields:
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["source","sql",subs="attributes,callouts,macros"]
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----
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include-tagged::{sql-specs}/docs.csv-spec[histogramDate]
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----
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