OpenSearch/docs/reference/search/suggesters.asciidoc

[[search-suggesters]]
=== Suggesters

The suggest feature suggests similar looking terms based on a provided
text by using a suggester. Parts of the suggest feature are still under
development.

The suggest request part is defined alongside the query part in a `_search`
request. If the query part is left out, only suggestions are returned.

NOTE: `_suggest` endpoint has been deprecated in favour of using suggest via
`_search` endpoint. In 5.0, the `_search` endpoint has been optimized for
suggest only search requests.

[source,js]
--------------------------------------------------
POST twitter/_search
{
  "query" : {
    "match": {
      "message": "tring out Elasticsearch"
    }
  },
  "suggest" : {
    "my-suggestion" : {
      "text" : "tring out Elasticsearch",
      "term" : {
        "field" : "message"
      }
    }
  }
}
--------------------------------------------------
// CONSOLE
// TEST[setup:twitter]

Several suggestions can be specified per request. Each suggestion is
identified with an arbitrary name. In the example below two suggestions
are requested. Both `my-suggest-1` and `my-suggest-2` suggestions use
the `term` suggester, but have a different `text`.

[source,js]
--------------------------------------------------
POST _search
{
  "suggest": {
    "my-suggest-1" : {
      "text" : "tring out Elasticsearch",
      "term" : {
        "field" : "message"
      }
    },
    "my-suggest-2" : {
      "text" : "kmichy",
      "term" : {
        "field" : "user"
      }
    }
  }
}
--------------------------------------------------
// CONSOLE
// TEST[setup:twitter]

The below suggest response example includes the suggestion response for
`my-suggest-1` and `my-suggest-2`. Each suggestion part contains
entries. Each entry is effectively a token from the suggest text and
contains the suggestion entry text, the original start offset and length
in the suggest text and if found an arbitrary number of options.

[source,js]
--------------------------------------------------
{
  "_shards": ...
  "hits": ...
  "took": 2,
  "timed_out": false,
  "suggest": {
    "my-suggest-1": [ {
      "text": "tring",
      "offset": 0,
      "length": 5,
      "options": [ {"text": "trying", "score": 0.8, "freq": 1 } ]
    }, {
      "text": "out",
      "offset": 6,
      "length": 3,
      "options": []
    }, {
      "text": "elasticsearch",
      "offset": 10,
      "length": 13,
      "options": []
    } ],
    "my-suggest-2": ...
  }
}
--------------------------------------------------
// TESTRESPONSE[s/"_shards": \.\.\./"_shards": "$body._shards",/]
// TESTRESPONSE[s/"hits": .../"hits": "$body.hits",/]
// TESTRESPONSE[s/"took": 2,/"took": "$body.took",/]
// TESTRESPONSE[s/"my-suggest-2": \.\.\./"my-suggest-2": "$body.suggest.my-suggest-2"/]


Each options array contains an option object that includes the
suggested text, its document frequency and score compared to the suggest
entry text. The meaning of the score depends on the used suggester. The
term suggester's score is based on the edit distance.

[float]
[[global-suggest]]
==== Global suggest text

To avoid repetition of the suggest text, it is possible to define a
global text. In the example below the suggest text is defined globally
and applies to the `my-suggest-1` and `my-suggest-2` suggestions.

[source,js]
--------------------------------------------------
POST _search
{
  "suggest": {
    "text" : "tring out Elasticsearch",
    "my-suggest-1" : {
      "term" : {
        "field" : "message"
      }
    },
    "my-suggest-2" : {
       "term" : {
        "field" : "user"
       }
    }
  }
}
--------------------------------------------------
// CONSOLE

The suggest text can in the above example also be specified as
suggestion specific option. The suggest text specified on suggestion
level override the suggest text on the global level.

include::suggesters/term-suggest.asciidoc[]

include::suggesters/phrase-suggest.asciidoc[]

include::suggesters/completion-suggest.asciidoc[]

include::suggesters/context-suggest.asciidoc[]

include::suggesters/misc.asciidoc[]