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Elastic Docs ›Elasticsearch Guide [8.15] ›Query DSL ›Term-level queries

Prefix query

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Prefix query

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Returns documents that contain a specific prefix in a provided field.

Example request

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The following search returns documents where the user.id field contains a term that begins with ki.

resp = client.search(
    query={
        "prefix": {
            "user.id": {
                "value": "ki"
            }
        }
    },
)
print(resp)
response = client.search(
  body: {
    query: {
      prefix: {
        'user.id' => {
          value: 'ki'
        }
      }
    }
  }
)
puts response
const response = await client.search({
  query: {
    prefix: {
      "user.id": {
        value: "ki",
      },
    },
  },
});
console.log(response);
GET /_search
{
  "query": {
    "prefix": {
      "user.id": {
        "value": "ki"
      }
    }
  }
}

Top-level parameters for prefix

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<field>
(Required, object) Field you wish to search.

Parameters for <field>

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value
(Required, string) Beginning characters of terms you wish to find in the provided <field>.
rewrite
(Optional, string) Method used to rewrite the query. For valid values and more information, see the rewrite parameter.
case_insensitive [7.10.0] Added in 7.10.0.
(Optional, Boolean) Allows ASCII case insensitive matching of the value with the indexed field values when set to true. Default is false which means the case sensitivity of matching depends on the underlying field’s mapping.

Notes

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Short request example

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You can simplify the prefix query syntax by combining the <field> and value parameters. For example:

resp = client.search(
    query={
        "prefix": {
            "user": "ki"
        }
    },
)
print(resp)
response = client.search(
  body: {
    query: {
      prefix: {
        user: 'ki'
      }
    }
  }
)
puts response
const response = await client.search({
  query: {
    prefix: {
      user: "ki",
    },
  },
});
console.log(response);
GET /_search
{
  "query": {
    "prefix" : { "user" : "ki" }
  }
}

Speed up prefix queries

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You can speed up prefix queries using the index_prefixes mapping parameter. If enabled, Elasticsearch indexes prefixes in a separate field, according to the configuration settings. This lets Elasticsearch run prefix queries more efficiently at the cost of a larger index.

Allow expensive queries

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Prefix queries will not be executed if search.allow_expensive_queries is set to false. However, if index_prefixes are enabled, an optimised query is built which is not considered slow, and will be executed in spite of this setting.

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