You're viewing version 2.17 of the OpenSearch documentation. This version is no longer maintained. For the latest version, see the current documentation. For information about OpenSearch version maintenance, see Release Schedule and Maintenance Policy.

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>`.
`boost`	Floating-point	A floating-point value that specifies the weight of this field toward the relevance score. Values above 1.0 increase the field’s relevance. Values between 0.0 and 1.0 decrease the field’s relevance. Default is 1.0.
`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, then prefix queries are not executed. If index_prefixes is enabled, then the search.allow_expensive_queries setting is ignored and an optimized query is built and run.