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Prefix query

Use the prefix query to search for terms that begin with a specific prefix. For example, the following query searches for documents in which the speaker field contains a term that starts with KING H:

GET shakespeare/_search
{
  "query": {
    "prefix": {
      "speaker": "KING H"
    }
  }
}

To provide parameters, you can use a query equivalent to the preceding one with the following extended syntax:

GET shakespeare/_search
{
  "query": {
    "prefix": {
      "speaker": {
        "value": "KING H"
      }
    }
  }
}

Parameters

The query accepts the name of the field (<field>) as a top-level parameter:

GET _search
{
  "query": {
    "prefix": {
      "<field>": {
        "value": "sample",
        ... 
      }
    }
  }
}

The <field> accepts the following parameters. All parameters except value are optional.

Parameter	Data type	Description
`value`	String	The term to search for in the field specified in `<field>`.
`case_insensitive`	Boolean	If `true`, allows case-insensitive matching of the value with the indexed field values. Default is `false` (case sensitivity is determined by the field’s mapping).
`rewrite`	String	Determines how OpenSearch rewrites and scores multi-term queries. Valid values are `constant_score`, `scoring_boolean`, `constant_score_boolean`, `top_terms_N`, `top_terms_boost_N`, and `top_terms_blended_freqs_N`. Default is `constant_score`.

If search.allow_expensive_queries is set to false, prefix queries are not run. If index_prefixes is enabled, the search.allow_expensive_queries setting is ignored and an optimized query is built and run.