# Elasticsearch Term suggester is not returning correct suggestions when one character is missing (instead of misspelling)

**URL:** <https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369>\
**Category:** Elasticsearch\
**Created:** [May 10, 2022, 3:28pm UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369 "2022-05-10T15:28:52Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![hesamrasouli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hesamrasouli/32/105501_2.png) [@hesamrasouli](https://discuss.elastic.co/u/hesamrasouli)\
**Post date:** [May 10, 2022, 3:28pm UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/1 "2022-05-10T15:28:52Z")

</div>

I'm using `Elasticsearch term suggester` for spell correction. my index contains huge list of ads. Each ad has subject and body fields. I've found a problematic example for which the suggester is not suggesting correct suggestions.

I have lots of ads whose subject contains word "soffa" and also 5 ads whose subject contain word "sofa". Ideally, when I send "sofa" (wrong spelling) as text to suggester, it should return "soffa" (correct spelling) as suggestions (since soffa is correct spell and most of ads contains "soffa" and only few ads contains "sofa" (wrong spell)).

Here is my suggester query body :

```auto
{
  "suggest": {
    "text": "sofa",
    "subjectSuggester": {
      "term": {
        "field": "subject",
        "suggest_mode": "popular",
        "min_word_length": 1
      }
    }
  }
}

```

When I send above query, I get below response :

```auto
{
    "took": 6,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 0,
            "relation": "eq"
        },
        "max_score": null,
        "hits": []
    },
    "suggest": {
        "subjectSuggester": [
            {
                "text": "sof",
                "offset": 0,
                "length": 4,
                "options": [
                    {
                        "text": "soff",
                        "score": 0.6666666,
                        "freq": 298
                    },
                    {
                        "text": "sol",
                        "score": 0.6666666,
                        "freq": 101
                    },
                    {
                        "text": "saf",
                        "score": 0.6666666,
                        "freq": 6
                    }
                ]
            }
        ]
    }
}

```

As you see in above response, it returned "soff" but not "soffa" although I have lots of docs whose subject contains "soffa".

I even played with parameters like `suggest_mode` and `string_distance` but still no luck.

I also used `phrase suggester` instead of `term suggester` but still same. Here is my phrase suggester query :

```auto
{
    "suggest": {
        "text": "sofa",
        "subjectuggester": {
            "phrase": {
                "field": "subject",
                "size": 10,
                "gram_size": 3,
                "direct_generator": [
                    {
                        "field": "subject.trigram",
                        "suggest_mode": "always",
                        "min_word_length":1
                    }
                ]
            }
        }
    }
}

```

I somehow think it doesn't work when one character is missing instead of being misspelled. in the "soffa" example, one "f" is missing. while it works fine for misspells e.g it works fine for "vovlo".  
When I send "vovlo" it gives me "volvo".

Any help would be hugely appreciated.

---

<div class="post-metadata">

**Author:** ![RabBit\_BR](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rabbit_br/32/82261_2.png) [@RabBit\_BR](https://discuss.elastic.co/u/RabBit_BR)\
**Post date:** [May 10, 2022, 6:00pm UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/2 "2022-05-10T18:00:33Z")

</div>

Hi!

Try change the " **string\_distance**".

```auto
{
  "suggest": {
    "text": "sof",
    "subjectSuggester": {
      "term": {
        "field": "title",
        "min_word_length":2,
        "string_distance":"ngram"
      }
    }
  }
}

```

> **[Suggesters | Elasticsearch Guide \[8.2\] | Elastic](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-suggesters.html#term-suggester)**

---

<div class="post-metadata">

**Author:** ![hesamrasouli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hesamrasouli/32/105501_2.png) [@hesamrasouli](https://discuss.elastic.co/u/hesamrasouli)\
**Post date:** [May 10, 2022, 6:15pm UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/4 "2022-05-10T18:15:57Z")

</div>

I already tried string\_distance:ngram didn’t work ☹

---

<div class="post-metadata">

**Author:** ![RabBit\_BR](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rabbit_br/32/82261_2.png) [@RabBit\_BR](https://discuss.elastic.co/u/RabBit_BR)\
**Post date:** [May 10, 2022, 6:42pm UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/5 "2022-05-10T18:42:00Z")

</div>

I'm doing a test with some data, "sol", "saf", "soffa" and I managed to have the correct suggestion.  
If you have a list of terms that I can test here I could understand what is happening.

---

<div class="post-metadata">

**Author:** ![hesamrasouli](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hesamrasouli/32/105501_2.png) [@hesamrasouli](https://discuss.elastic.co/u/hesamrasouli)\
**Post date:** [May 11, 2022, 11:24am UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/6 "2022-05-11T11:24:19Z")

</div>

I've found the workaround myself.  
I added ngram filter and analyzer with `max_shingle_size` 3 which means trigram, then added a subfield with that analyzer (trigram) and performed suggester query on that field (instead of actual field) and it worked.

Here is the mapping changes :

```auto
{
    "settings": {
        "analysis": {
            "filter": {
                "shingle": {
                    "type": "shingle",
                    "min_shingle_size": 2,
                    "max_shingle_size": 3
                }
            },
            "analyzer": {
                "trigram": {
                    "type": "custom",
                    "tokenizer": "standard",
                    "filter": [
                        "lowercase",
                        "shingle"
                    ],
                    "char_filter": [
                        "diacritical_marks_filter"
                    ]
                }
            }
        }
    },
    "mappings": {
        "properties": {
            "subject": {
                "type": "text",
                "fields": {
                    "trigram": {
                        "type": "text",
                        "analyzer": "trigram"
                    }
                }
            }
        }
    }
}

```

And here is my corrected query :

```auto
{
  "suggest": {
    "text": "sofa",
    "subjectSuggester": {
      "term": {
        "field": "subject.trigram",
        "suggest_mode": "popular",
        "min_word_length": 1,
        "string_distance": "ngram"
      }
    }
  }
}

```

Note that I'm performing suggester to `subject.trigram` instead of `subject` itself.

Here is the result :

```auto
{
    "suggest": {
        "subjectSuggester": [
            {
                "text": "sofa",
                "offset": 0,
                "length": 4,
                "options": [
                    {
                        "text": "soffa",
                        "score": 0.8,
                        "freq": 282
                    },
                    {
                        "text": "soffan",
                        "score": 0.6666666,
                        "freq": 5
                    },
                    {
                        "text": "som",
                        "score": 0.625,
                        "freq": 102
                    },
                    {
                        "text": "sol",
                        "score": 0.625,
                        "freq": 82
                    },
                    {
                        "text": "sony",
                        "score": 0.625,
                        "freq": 50
                    }
                ]
            }
        ]
    }
}

```

As you can see above soffa appears as first suggestion.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [June 8, 2022, 11:24am UTC](https://discuss.elastic.co/t/elasticsearch-term-suggester-is-not-returning-correct-suggestions-when-one-character-is-missing-instead-of-misspelling/304369/7 "2022-06-08T11:24:36Z")

</div>

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