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* Document nested expressions for stats * More docs * Apply suggestions from review - count-distinct.asciidoc - Content restructured, moving the section about approximate counts to end of doc. - count.asciidoc - Clarified that omitting the `expression` parameter in `COUNT` is equivalent to `COUNT(*)`, which counts the number of rows. - percentile.asciidoc - Moved the note about `PERCENTILE` being approximate and non-deterministic to end of doc. - stats.asciidoc - Clarified the `STATS` command - Added a note indicating that individual `null` values are skipped during aggregation * Comment out mentioning a buggy behavior * Update sum with inline function example, update test file * Fix typo * Delete line * Simplify wording * Fix conflict fix typo --------- Co-authored-by: Liam Thompson <leemthompo@gmail.com> Co-authored-by: Liam Thompson <32779855+leemthompo@users.noreply.github.com>
52 lines
1.3 KiB
Text
52 lines
1.3 KiB
Text
[discrete]
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[[esql-agg-median]]
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=== `MEDIAN`
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*Syntax*
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[source,esql]
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----
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MEDIAN(expression)
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----
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*Parameters*
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`expression`::
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Expression from which to return the median value.
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*Description*
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Returns the value that is greater than half of all values and less than half of
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all values, also known as the 50% <<esql-agg-percentile>>.
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NOTE: Like <<esql-agg-percentile>>, `MEDIAN` is <<esql-agg-percentile-approximate,usually approximate>>.
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[WARNING]
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====
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`MEDIAN` is also {wikipedia}/Nondeterministic_algorithm[non-deterministic].
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This means you can get slightly different results using the same data.
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====
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*Example*
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[source.merge.styled,esql]
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----
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include::{esql-specs}/stats_percentile.csv-spec[tag=median]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/stats_percentile.csv-spec[tag=median-result]
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|===
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The expression can use inline functions. For example, to calculate the median of
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the maximum values of a multivalued column, first use `MV_MAX` to get the
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maximum value per row, and use the result with the `MEDIAN` function:
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[source.merge.styled,esql]
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----
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include::{esql-specs}/stats_percentile.csv-spec[tag=docsStatsMedianNestedExpression]
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----
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[%header.monospaced.styled,format=dsv,separator=|]
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|===
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include::{esql-specs}/stats_percentile.csv-spec[tag=docsStatsMedianNestedExpression-result]
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|===
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