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diff --git a/docs/reference/aggregations/metrics/stats-aggregation.asciidoc b/docs/reference/aggregations/metrics/stats-aggregation.asciidoc new file mode 100644 index 0000000000..7fbdecd601 --- /dev/null +++ b/docs/reference/aggregations/metrics/stats-aggregation.asciidoc @@ -0,0 +1,81 @@ +[[search-aggregations-metrics-stats-aggregation]] +=== Stats Aggregation + +A `multi-value` metrics aggregation that computes stats over numeric values extracted from the aggregated documents. These values can be extracted either from specific numeric fields in the documents, or be generated by a provided script. + +The stats that are returned consist of: `min`, `max`, `sum`, `count` and `avg`. + +Assuming the data consists of documents representing exams grades (between 0 and 100) of students + +[source,js] +-------------------------------------------------- +{ + "aggs" : { + "grades_stats" : { "stats" : { "field" : "grade" } } + } +} +-------------------------------------------------- + +The above aggregation computes the grades statistics over all documents. The aggregation type is `stats` and the `field` setting defines the numeric field of the documents the stats will be computed on. The above will return the following: + + +[source,js] +-------------------------------------------------- +{ + ... + + "aggregations": { + "grades_stats": { + "count": 6, + "min": 60, + "max": 98, + "avg": 78.5, + "sum": 471 + } + } +} +-------------------------------------------------- + +The name of the aggregation (`grades_stats` above) also serves as the key by which the aggregation result can be retrieved from the returned response. + +==== Script + +Computing the grades stats based on a script: + +[source,js] +-------------------------------------------------- +{ + ..., + + "aggs" : { + "grades_stats" : { "stats" : { "script" : "doc['grade'].value" } } + } +} +-------------------------------------------------- + +TIP: The `script` parameter expects an inline script. Use `script_id` for indexed scripts and `script_file` for scripts in the `config/scripts/` directory. + +===== Value Script + +It turned out that the exam was way above the level of the students and a grade correction needs to be applied. We can use a value script to get the new stats: + +[source,js] +-------------------------------------------------- +{ + "aggs" : { + ... + + "aggs" : { + "grades_stats" : { + "stats" : { + "field" : "grade", + "script" : "_value * correction", + "params" : { + "correction" : 1.2 + } + } + } + } + } +} +--------------------------------------------------
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