elasticsearch/docs/reference/query-languages/query-dsl/query-dsl-combined-fields-query.md

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navigation_title: "Combined fields" mapped_pages:

• https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-combined-fields-query.html ---

Combined fields [query-dsl-combined-fields-query]

The combined_fields query supports searching multiple text fields as if their contents had been indexed into one combined field. The query takes a term-centric view of the input string: first it analyzes the query string into individual terms, then looks for each term in any of the fields. This query is particularly useful when a match could span multiple text fields, for example the title, abstract, and body of an article:

GET /_search
{
  "query": {
    "combined_fields" : {
      "query":      "database systems",
      "fields":     [ "title", "abstract", "body"],
      "operator":   "and"
    }
  }
}

The combined_fields query takes a principled approach to scoring based on the simple BM25F formula described in The Probabilistic Relevance Framework: BM25 and Beyond. When scoring matches, the query combines term and collection statistics across fields to score each match as if the specified fields had been indexed into a single, combined field. This scoring is a best attempt; combined_fields makes some approximations and scores will not obey the BM25F model perfectly.

::::{admonition} Field number limit :class: warning

By default, there is a limit to the number of clauses a query can contain. This limit is defined by the indices.query.bool.max_clause_count setting, which defaults to 4096. For combined fields queries, the number of clauses is calculated as the number of fields multiplied by the number of terms.

::::

Per-field boosting [_per_field_boosting]

Field boosts are interpreted according to the combined field model. For example, if the title field has a boost of 2, the score is calculated as if each term in the title appeared twice in the synthetic combined field.

GET /_search
{
  "query": {
    "combined_fields" : {
      "query" : "distributed consensus",
      "fields" : [ "title^2", "body" ] <1>
    }
  }
}

1. Individual fields can be boosted with the caret (^) notation.

::::{note} The combined_fields query requires that field boosts are greater than or equal to 1.0. Field boosts are allowed to be fractional. ::::

Top-level parameters for combined_fields [combined-field-top-level-params]

fields : (Required, array of strings) List of fields to search. Field wildcard patterns are allowed. Only text fields are supported, and they must all have the same search analyzer.

query : (Required, string) Text to search for in the provided <fields>.

The combined_fields query analyzes the provided text before performing a search.

auto_generate_synonyms_phrase_query : (Optional, Boolean) If true, match phrase queries are automatically created for multi-term synonyms. Defaults to true.

See Use synonyms with match query for an example.

operator : (Optional, string) Boolean logic used to interpret text in the query value. Valid values are:

• or (Default) For example, a query value of database systems is interpreted as database OR systems.
• and For example, a query value of database systems is interpreted as database AND systems.

minimum_should_match : (Optional, string) Minimum number of clauses that must match for a document to be returned. See the minimum_should_match parameter for valid values and more information.

zero_terms_query : (Optional, string) Indicates whether no documents are returned if the analyzer removes all tokens, such as when using a stop filter. Valid values are:

• none (Default) No documents are returned if the analyzer removes all tokens.
• all Returns all documents, similar to a match_all query.

See Zero terms query for an example.

Comparison to multi_match query [_comparison_to_multi_match_query]

The combined_fields query provides a principled way of matching and scoring across multiple text fields. To support this, it requires that all fields have the same search analyzer.

If you want a single query that handles fields of different types like keywords or numbers, then the multi_match query may be a better fit. It supports both text and non-text fields, and accepts text fields that do not share the same analyzer.

The main multi_match modes best_fields and most_fields take a field-centric view of the query. In contrast, combined_fields is term-centric: operator and minimum_should_match are applied per-term, instead of per-field. Concretely, a query like

GET /_search
{
  "query": {
    "combined_fields" : {
      "query":      "database systems",
      "fields":     [ "title", "abstract"],
      "operator":   "and"
    }
  }
}

is executed as:

+(combined("database", fields:["title" "abstract"]))
+(combined("systems", fields:["title", "abstract"]))

In other words, each term must be present in at least one field for a document to match.

The cross_fields multi_match mode also takes a term-centric approach and applies operator and minimum_should_match per-term. The main advantage of combined_fields over cross_fields is its robust and interpretable approach to scoring based on the BM25F algorithm.

::::{admonition} Custom similarities :class: note

The combined_fields query currently only supports the BM25 similarity, which is the default unless a custom similarity is configured. Per-field similarities are also not allowed. Using combined_fields in either of these cases will result in an error.

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