[[query-dsl-bool-query]]
=== Bool Query

A query that matches documents matching boolean combinations of other
queries. The bool query maps to Lucene `BooleanQuery`. It is built using
one or more boolean clauses, each clause with a typed occurrence. The
occurrence types are:

[cols="<,<",options="header",]
|=======================================================================
|Occur |Description
|`must` |The clause (query) must appear in matching documents and will
contribute to the score.

|`filter` |The clause (query) must appear in matching documents. However unlike
`must` the score of the query will be ignored.

|`should` |The clause (query) should appear in the matching document. In
a boolean query with no `must` or `filter` clauses, one or more `should` clauses
must match a document. The minimum number of should clauses to match can
be set using the
<<query-dsl-minimum-should-match,`minimum_should_match`>>
parameter.

|`must_not` |The clause (query) must not appear in the matching
documents.
|=======================================================================

[IMPORTANT]
.Bool query in filter context
========================================================================
If this query is used in a filter context and it has `should`
clauses then at least one `should` clause is required to match.
========================================================================

The bool query also supports `disable_coord` parameter (defaults to
`false`). Basically the coord similarity computes a score factor based
on the fraction of all query terms that a document contains. See Lucene
`BooleanQuery` for more details.

The `bool` query takes a _more-matches-is-better_ approach, so the score from
each matching `must` or `should` clause will be added together to provide the 
final `_score` for each document.

[source,js]
--------------------------------------------------
{
    "bool" : {
        "must" : {
            "term" : { "user" : "kimchy" }
        },
        "filter": {
            "term" : { "tag" : "tech" }
        },
        "must_not" : {
            "range" : {
                "age" : { "from" : 10, "to" : 20 }
            }
        },
        "should" : [
            {
                "term" : { "tag" : "wow" }
            },
            {
                "term" : { "tag" : "elasticsearch" }
            }
        ],
        "minimum_should_match" : 1,
        "boost" : 1.0
    }
}
--------------------------------------------------

==== Scoring with `bool.filter` 

Queries specified under the `filter` element have no effect on scoring --
scores are returned as `0`.  Scores are only affected by the query that has
been specified.  For instance, all three of the following queries return 
all documents where the `status` field contains the term `active`. 

This first query assigns a score of `0` to all documents, as no scoring
query has been specified: 

[source,json]
---------------------------------
GET _search
{
  "query": {
    "bool": {
      "filter": {
        "term": {
          "status": "active"
        }
      }
    }
  }
}
---------------------------------
// AUTOSENSE

This `bool` query has a `match_all` query, which assigns a score of `1.0` to 
all documents.

[source,json]
---------------------------------
GET _search
{
  "query": {
    "bool": {
      "must": {
        "match_all": {}
      },
      "filter": {
        "term": {
          "status": "active"
        }
      }
    }
  }
}
---------------------------------
// AUTOSENSE

This `constant_score` query behaves in exactly the same way as the second example above.  
The `constant_score` query assigns a score of `1.0` to all documents matched
by the filter. 

[source,json]
---------------------------------
GET _search
{
  "query": {
    "constant_score": {
      "filter": {
        "term": {
          "status": "active"
        }
      }
    }
  }
}
---------------------------------
// AUTOSENSE

==== Using named queries to see which clauses matched

If you need to know which of the clauses in the bool query matched the documents
returned from the query, you can use
<<search-request-named-queries-and-filters,named queries>> to assign a name to
each clause.