Category: How do I do X?
Updated

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Get List of Distinct Values From Existing Query Result Set

Issue

I have an Elasticsearch database query and I want to generate a list of unique values for a specific field. I tried using the "collapse" method but couldn't get it to work. I want to work with the existing results on the client-side and not re-run the query on the server.

Resolution

To generate a list of distinct values for the author_id field, two approaches can be used depending on your needs:

Using "terms" Aggregation:

  1. You can use Elasticsearch's "terms" aggregation to get a count of each unique author_id.
  2. This method requires adding an aggregation to your existing query. You need to add a "terms" key with a "field" key specifying the field you want distinct values for, in this case, author_id.

  3. Example of an Elasticsearch query with "terms" aggregation:

    {
  "aggs": {
    "distinct_author_ids": {
      "terms": {
        "field": "author_id"
      }
    }
  }
}

This query will return an aggregation of distinct author_id values.

Using "Collapse" Method:

  • The "collapse" method can be used to collapse the search results based on the author_id field.
  • This approach groups the results by author_id, ensuring only one record is returned for each unique author_id.

  • Example of using the "collapse" method:

    {
  "query": {
    // Your existing query
  },
  "collapse": {
    "field": "author_id"
  }
}