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35a58d874e
This change unifies the way scripts and templates are specified for all instances in the codebase. It builds on the Script class added previously and adds request building and parsing support as well as the ability to transfer script objects between nodes. It also adds a Template class which aims to provide the same functionality for template APIs Closes #11091
128 lines
3.6 KiB
Plaintext
128 lines
3.6 KiB
Plaintext
[[search-aggregations-metrics-stats-aggregation]]
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=== Stats Aggregation
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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.
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The stats that are returned consist of: `min`, `max`, `sum`, `count` and `avg`.
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Assuming the data consists of documents representing exams grades (between 0 and 100) of students
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[source,js]
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--------------------------------------------------
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{
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"aggs" : {
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"grades_stats" : { "stats" : { "field" : "grade" } }
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}
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}
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--------------------------------------------------
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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:
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[source,js]
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--------------------------------------------------
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{
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...
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"aggregations": {
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"grades_stats": {
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"count": 6,
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"min": 60,
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"max": 98,
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"avg": 78.5,
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"sum": 471
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}
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}
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}
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--------------------------------------------------
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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.
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==== Script
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Computing the grades stats based on a script:
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[source,js]
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--------------------------------------------------
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{
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...,
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"aggs" : {
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"grades_stats" : { "stats" : { "script" : "doc['grade'].value" } }
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}
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}
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--------------------------------------------------
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This will interpret the `script` parameter as an `inline` script with the default script language and no script parameters. To use a file script use the following syntax:
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[source,js]
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--------------------------------------------------
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{
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...,
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"aggs" : {
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"grades_stats" : {
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"stats" : {
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"script" : {
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"file": "my_script",
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"params" : {
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"field" : "grade"
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}
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}
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}
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}
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}
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}
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--------------------------------------------------
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TIP: for indexed scripts replace the `file` parameter with an `id` parameter.
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===== Value Script
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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:
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[source,js]
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--------------------------------------------------
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{
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"aggs" : {
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...
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"aggs" : {
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"grades_stats" : {
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"stats" : {
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"field" : "grade",
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"script" :
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"inline": "_value * correction",
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"params" : {
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"correction" : 1.2
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}
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}
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}
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}
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}
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}
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}
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--------------------------------------------------
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==== Missing value
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The `missing` parameter defines how documents that are missing a value should be treated.
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By default they will be ignored but it is also possible to treat them as if they
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had a value.
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[source,js]
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--------------------------------------------------
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{
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"aggs" : {
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"grades_stats" : {
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"stats" : {
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"field" : "grade",
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"missing": 0 <1>
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}
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}
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}
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}
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--------------------------------------------------
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<1> Documents without a value in the `grade` field will fall into the same bucket as documents that have the value `0`.
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