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Elastic Docs ›Elasticsearch Guide [7.9] ›Aggregations ›Bucket Aggregations

Filters aggregation

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Filters aggregation

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Defines a multi bucket aggregation where each bucket is associated with a filter. Each bucket will collect all documents that match its associated filter.

Example:

PUT /logs/_bulk?refresh
{ "index" : { "_id" : 1 } }
{ "body" : "warning: page could not be rendered" }
{ "index" : { "_id" : 2 } }
{ "body" : "authentication error" }
{ "index" : { "_id" : 3 } }
{ "body" : "warning: connection timed out" }

GET logs/_search
{
  "size": 0,
  "aggs" : {
    "messages" : {
      "filters" : {
        "filters" : {
          "errors" :   { "match" : { "body" : "error"   }},
          "warnings" : { "match" : { "body" : "warning" }}
        }
      }
    }
  }
}

In the above example, we analyze log messages. The aggregation will build two collection (buckets) of log messages - one for all those containing an error, and another for all those containing a warning.

Response:

{
  "took": 9,
  "timed_out": false,
  "_shards": ...,
  "hits": ...,
  "aggregations": {
    "messages": {
      "buckets": {
        "errors": {
          "doc_count": 1
        },
        "warnings": {
          "doc_count": 2
        }
      }
    }
  }
}

Anonymous filters

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The filters field can also be provided as an array of filters, as in the following request:

GET logs/_search
{
  "size": 0,
  "aggs" : {
    "messages" : {
      "filters" : {
        "filters" : [
          { "match" : { "body" : "error"   }},
          { "match" : { "body" : "warning" }}
        ]
      }
    }
  }
}

The filtered buckets are returned in the same order as provided in the request. The response for this example would be:

{
  "took": 4,
  "timed_out": false,
  "_shards": ...,
  "hits": ...,
  "aggregations": {
    "messages": {
      "buckets": [
        {
          "doc_count": 1
        },
        {
          "doc_count": 2
        }
      ]
    }
  }
}

Other Bucket

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The other_bucket parameter can be set to add a bucket to the response which will contain all documents that do not match any of the given filters. The value of this parameter can be as follows:

false
Does not compute the other bucket
true
Returns the other bucket either in a bucket (named _other_ by default) if named filters are being used, or as the last bucket if anonymous filters are being used

The other_bucket_key parameter can be used to set the key for the other bucket to a value other than the default _other_. Setting this parameter will implicitly set the other_bucket parameter to true.

The following snippet shows a response where the other bucket is requested to be named other_messages.

PUT logs/_doc/4?refresh
{
  "body": "info: user Bob logged out"
}

GET logs/_search
{
  "size": 0,
  "aggs" : {
    "messages" : {
      "filters" : {
        "other_bucket_key": "other_messages",
        "filters" : {
          "errors" :   { "match" : { "body" : "error"   }},
          "warnings" : { "match" : { "body" : "warning" }}
        }
      }
    }
  }
}

The response would be something like the following:

{
  "took": 3,
  "timed_out": false,
  "_shards": ...,
  "hits": ...,
  "aggregations": {
    "messages": {
      "buckets": {
        "errors": {
          "doc_count": 1
        },
        "warnings": {
          "doc_count": 2
        },
        "other_messages": {
          "doc_count": 1
        }
      }
    }
  }
}
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