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I have address doc type which has city as field. The city field uses analyser

"keyword_analyzer": {
  "tokenizer": "keyword", # So that we don't split multi word city name
  "filter": ["lowercase"] # The search needs to case insensitive
}

How can I get any address which matches the give city 'X' or city is null. In sql it would be written as

SELECT * FROM address
WHERE city = 'X' or city IS NULL

I guess I have to use match query to get city ='X' and 'missing' filter to get city IS NULL. How can I combine this?

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1 Answer 1

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Elasticsearch allows to combine queries with the bool query. Bool query has three fields:

  • must (AND)
  • should (OR)
  • must_not (AND NOT)

The following elasticsearch query is a boolean query containing a should field, with two sub-queries:

  • the first selects items with city field containing at least one token == "myCity"
  • the second selects items without city field

Results of this query will be equivalent to city = 'mycity' OR city IS NULL:

{
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "city": "mycity"
          }
        },
        {
          "filtered": {
            "query": {
              "match_all": {}
            },
            "filter": {
              "missing": {
                "field": "city"
              }
            }
          }
        }
      ]
    }
  }
}

Some useful resources:

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