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Suggesters
editSuggesters
editThe 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 either defined alongside the query part in a
_search
request or via the REST _suggest
endpoint.
POST twitter/_search { "query" : { "match": { "message": "tring out Elasticsearch" } }, "suggest" : { "my-suggestion" : { "text" : "trying out Elasticsearch", "term" : { "field" : "message" } } } }
Suggest requests executed against the _suggest
endpoint should omit
the surrounding suggest
element which is only used if the suggest
request is part of a search.
POST _suggest { "my-suggestion" : { "text" : "tring out Elasticsearch", "term" : { "field" : "message" } } }
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
.
POST _suggest { "my-suggest-1" : { "text" : "tring out Elasticsearch", "term" : { "field" : "message" } }, "my-suggest-2" : { "text" : "kmichy", "term" : { "field" : "user" } } }
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.
{ "_shards": ... "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": ... }
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.
Global suggest text
editTo 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.
POST _suggest { "text" : "tring out Elasticsearch", "my-suggest-1" : { "term" : { "field" : "message" } }, "my-suggest-2" : { "term" : { "field" : "user" } } }
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.