CODEWITHSUNDEEP
elasticsearchaggregation
Istiak Mahmood
Istiak Mahmood

Reputation: 2422

elasticsearch unique values aggregation

I want to get the unique values from elasticsearch in the field named "name", i do not know how can i put the condition where the values have to be unique.

The purpose of this work is the fetch all the unique names from the elasticsearch database.

So basically what i need is a aggregation query that fetch the unique values

Can someone help me to fix this issue, thanks a lot in advanced.

Upvotes: 0

Views: 2261

Answers (1)

ThomasC
ThomasC

Reputation: 8165

You can use a terms aggregation on a field which is not_analyzed.

However, this is by default limited to the 10 most popular terms. You can change this by updating the size parameter of the terms aggregation. Setting it to 0 will allow you to have up to Integer.MAX_VALUE different terms (see the documentation here).

Here is an example mapping:

POST terms
{
  "mappings":{
    "test":{
      "properties":{
        "title":{
          "type":"string",
          "index":"not_analyzed"
        }
      }
    }
  }
}

Adding some documents :

POST terms/test
{
  "title":"Foundation"
}


POST terms/test
{
  "title":"Foundation & Empire"
}

Finally, the request :

POST terms/_search?search_type=count
{
  "aggs": {
    "By Title": {
      "terms": {
        "field": "title",
        "size": 0
      }
    }
  }
}

will give you what you need :

"aggregations": {
      "By Title": {
         "doc_count_error_upper_bound": 0,
         "sum_other_doc_count": 0,
         "buckets": [
            {
               "key": "Foundation",
               "doc_count": 1
            },
            {
               "key": "Foundation & Empire",
               "doc_count": 1
            }
         ]
      }
   }

Be aware that if you have a large number of terms, this request will be very expensive to execute.

Upvotes: 1

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