elasticsearch/docs/reference/aggregations/pipeline/bucket-selector-aggregation.asciidoc
edh-oss 62a471aefe
Update JSON parser and snippets (#77983)
Related to issue  #77823

This does the following:

- Updates several asciidoc files that contained code snippets with
  invalid JSON, most involving unnecessary trailing commas.

- Makes the switch from the Groovy JSON parser to the Jackson parser,
  pursuant to the general goal of eliminating Groovy dependence.

- Makes testing of JSON validity at build time more strict.

Note that this update still allows backslash escaping for any
character. Currently that matters because of the file
"docs/reference/ml/anomaly-detection/apis/get-datafeed-stats.asciidoc",
specifically this part:

    "attributes" : {
      "ml.machine_memory" :
        "$body.datafeeds.0.node.attributes.ml\.machine_memory",
      "ml.max_open_jobs" : "512"
    }

It's not clear to me what change, if any, is appropriate there. So,
I've left in the escaped period and configured the parser to ignore
it for the time being.
2021-09-20 11:08:26 +01:00

119 lines
3.7 KiB
Text

[[search-aggregations-pipeline-bucket-selector-aggregation]]
=== Bucket selector aggregation
++++
<titleabbrev>Bucket selector</titleabbrev>
++++
A parent pipeline aggregation which executes a script which determines whether the current bucket will be retained
in the parent multi-bucket aggregation. The specified metric must be numeric and the script must return a boolean value.
If the script language is `expression` then a numeric return value is permitted. In this case 0.0 will be evaluated as `false`
and all other values will evaluate to true.
NOTE: The bucket_selector aggregation, like all pipeline aggregations, executes after all other sibling aggregations. This means that
using the bucket_selector aggregation to filter the returned buckets in the response does not save on execution time running the aggregations.
==== Syntax
A `bucket_selector` aggregation looks like this in isolation:
[source,js]
--------------------------------------------------
{
"bucket_selector": {
"buckets_path": {
"my_var1": "the_sum", <1>
"my_var2": "the_value_count"
},
"script": "params.my_var1 > params.my_var2"
}
}
--------------------------------------------------
// NOTCONSOLE
<1> Here, `my_var1` is the name of the variable for this buckets path to use in the script, `the_sum` is the path to
the metrics to use for that variable.
[[bucket-selector-params]]
.`bucket_selector` Parameters
[options="header"]
|===
|Parameter Name |Description |Required |Default Value
|`script` |The script to run for this aggregation. The script can be inline, file or indexed. (see <<modules-scripting>>
for more details) |Required |
|`buckets_path` |A map of script variables and their associated path to the buckets we wish to use for the variable
(see <<buckets-path-syntax>> for more details) |Required |
|`gap_policy` |The policy to apply when gaps are found in the data (see <<gap-policy>> for more
details)|Optional |`skip`
|===
The following snippet only retains buckets where the total sales for the month is more than 200:
[source,console]
--------------------------------------------------
POST /sales/_search
{
"size": 0,
"aggs": {
"sales_per_month": {
"date_histogram": {
"field": "date",
"calendar_interval": "month"
},
"aggs": {
"total_sales": {
"sum": {
"field": "price"
}
},
"sales_bucket_filter": {
"bucket_selector": {
"buckets_path": {
"totalSales": "total_sales"
},
"script": "params.totalSales > 200"
}
}
}
}
}
}
--------------------------------------------------
// TEST[setup:sales]
And the following may be the response:
[source,console-result]
--------------------------------------------------
{
"took": 11,
"timed_out": false,
"_shards": ...,
"hits": ...,
"aggregations": {
"sales_per_month": {
"buckets": [
{
"key_as_string": "2015/01/01 00:00:00",
"key": 1420070400000,
"doc_count": 3,
"total_sales": {
"value": 550.0
}
},<1>
{
"key_as_string": "2015/03/01 00:00:00",
"key": 1425168000000,
"doc_count": 2,
"total_sales": {
"value": 375.0
}
}
]
}
}
}
--------------------------------------------------
// TESTRESPONSE[s/"took": 11/"took": $body.took/]
// TESTRESPONSE[s/"_shards": \.\.\./"_shards": $body._shards/]
// TESTRESPONSE[s/"hits": \.\.\./"hits": $body.hits/]
<1> Bucket for `2015/02/01 00:00:00` has been removed as its total sales was less than 200