[[query-dsl-semantic-query]]
=== Semantic query
++++
<titleabbrev>Semantic</titleabbrev>
++++

beta[]

The `semantic` query type enables you to perform <<semantic-search,semantic search>> on data stored in a <<semantic-text,`semantic_text`>> field.


[discrete]
[[semantic-query-example]]
==== Example request

[source,console]
------------------------------------------------------------
GET my-index-000001/_search
{
  "query": {
    "semantic": {
      "field": "inference_field",
      "query": "Best surfing places"
    }
  }
}
------------------------------------------------------------
// TEST[skip: Requires inference endpoints]


[discrete]
[[semantic-query-params]]
==== Top-level parameters for `semantic`

`field`::
(Required, string)
The `semantic_text` field to perform the query on.

`query`::
(Required, string)
The query text to be searched for on the field.


Refer to <<semantic-search-semantic-text,this tutorial>> to learn more about semantic search using `semantic_text` and `semantic` query.

[discrete]
[[hybrid-search-semantic]]
==== Hybrid search with the `semantic` query

The `semantic` query can be used as a part of a hybrid search where the `semantic` query is combined with lexical queries.
For example, the query below finds documents with the `title` field matching "mountain lake", and combines them with results from a semantic search on the field `title_semantic`, that is a `semantic_text` field.
The combined documents are then scored, and the top 3 top scored documents are returned.

[source,console]
------------------------------------------------------------
POST my-index/_search
{
  "size" : 3,
  "query": {
    "bool": {
      "should": [
        {
          "match": {
            "title": {
              "query": "mountain lake",
              "boost": 1
            }
          }
        },
        {
          "semantic": {
            "field": "title_semantic",
            "query": "mountain lake",
            "boost": 2
          }
        }
      ]
    }
  }
}
------------------------------------------------------------
// TEST[skip: Requires inference endpoints]

You can also use semantic_text as part of <<rrf,Reciprocal Rank Fusion>> to make ranking relevant results easier:

[source,console]
------------------------------------------------------------
GET my-index/_search
{
  "retriever": {
    "rrf": {
      "retrievers": [
        {
          "standard": {
            "query": {
              "term": {
                "text": "shoes"
              }
            }
          }
        },
        {
          "standard": {
            "query": {
              "semantic": {
                "field": "semantic_field",
                "query": "shoes"
              }
            }
          }
        }
      ],
      "rank_window_size": 50,
      "rank_constant": 20
    }
  }
}
------------------------------------------------------------
// TEST[skip: Requires inference endpoints]


[discrete]
[[advanced-search]]
==== Advanced search on `semantic_text` fields

The `semantic` query uses default settings for searching on `semantic_text` fields for ease of use.
If you want to fine-tune a search on a `semantic_text` field, you need to know the task type used by the `inference_id` configured in `semantic_text`.
You can find the task type using the <<get-inference-api>>, and check the `task_type` associated with the {infer} service.
Depending on the `task_type`, use either the <<query-dsl-sparse-vector-query,`sparse_vector`>> or the <<query-dsl-knn-query,`knn`>> query for greater flexibility and customization.

NOTE: While it is possible to use the `sparse_vector` query or the `knn` query
on a `semantic_text` field, it is not supported to use the `semantic_query` on a
`sparse_vector` or `dense_vector` field type.


[discrete]
[[search-sparse-inference]]
===== Search with `sparse_embedding` inference

When the {infer} endpoint uses a `sparse_embedding` model, you can use a <<query-dsl-sparse-vector-query,`sparse_vector` query>> on a <<semantic-text,`semantic_text`>> field in the following way:

[source,console]
------------------------------------------------------------
GET test-index/_search
{
  "query": {
    "nested": {
      "path": "inference_field.inference.chunks",
      "query": {
        "sparse_vector": {
          "field": "inference_field.inference.chunks.embeddings",
          "inference_id": "my-inference-id",
          "query": "mountain lake"
        }
      }
    }
  }
}
------------------------------------------------------------
// TEST[skip: Requires inference endpoints]

You can customize the `sparse_vector` query to include specific settings, like <<sparse-vector-query-with-pruning-config-and-rescore-example,pruning configuration>>.


[discrete]
[[search-text-inferece]]
===== Search with `text_embedding` inference

When the {infer} endpoint uses a `text_embedding` model, you can use a <<query-dsl-knn-query,`knn` query>> on a `semantic_text` field in the following way:

[source,console]
------------------------------------------------------------
GET test-index/_search
{
  "query": {
    "nested": {
      "path": "inference_field.inference.chunks",
      "query": {
        "knn": {
          "field": "inference_field.inference.chunks.embeddings",
          "query_vector_builder": {
            "text_embedding": {
              "model_id": "my_inference_id",
	      "model_text": "mountain lake"
            }
          }
        }
      }
    }
  }
}
------------------------------------------------------------
// TEST[skip: Requires inference endpoints]

You can customize the `knn` query to include specific settings, like `num_candidates` and `k`.