# Elasticsearch highlighting on ngram filter is wrwong if min\_gram is set to 1

**URL:** <https://discuss.elastic.co/t/elasticsearch-highlighting-on-ngram-filter-is-wrwong-if-min-gram-is-set-to-1/10059>\
**Category:** Elasticsearch\
**Created:** [December 13, 2012, 1:43am UTC](https://discuss.elastic.co/t/elasticsearch-highlighting-on-ngram-filter-is-wrwong-if-min-gram-is-set-to-1/10059 "2012-12-13T01:43:02Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![concept47](https://avatars.discourse-cdn.com/v4/letter/c/f6c823/32.png) [@concept47](https://discuss.elastic.co/u/concept47)\
**Post date:** [December 13, 2012, 1:43am UTC](https://discuss.elastic.co/t/elasticsearch-highlighting-on-ngram-filter-is-wrwong-if-min-gram-is-set-to-1/10059/1 "2012-12-13T01:43:02Z")

</div>

So I have this index

```
{
  "settings":{
    "index":{
      "number_of_replicas":0,
      "analysis":{
        "analyzer":{
          "default":{
            "type":"custom",
            "tokenizer":"keyword",
            "filter":[
              "lowercase",
              "my_ngram"
            ]
          }
        },
        "filter":{
          "my_ngram":{
            "type":"nGram",
            "min_gram":2,
            "max_gram":20
          }
        }
      }
    }
  }
}

```

and I'm performing this search through the tire gem

```
{
   "query":{
      "query_string":{
         "query":"xyz",
         "default_operator":"AND"
      }
   },
   "sort":[
      {
         "count":"desc"
      }
   ],
   "filter":{
      "term":{
         "active":true,
         "_type":null
      }
   },
   "highlight":{
      "fields":{
         "name":{

         }
      },
      "pre_tags":[
         "<strong>"
      ],
      "post_tags":[
         "</strong>"
      ]
   }
}

```

and I have two posts that should match named 'xyz post' and 'xyz question'  
When I perform this search, I get the highlighted fields back properly

```
<strong>xyz</strong> question
<strong>xyz</strong> post

```

Now here's the thing ... as soon as I change min\_gram to 1 in my index and  
reindex. the highlighted fields start coming back as this

```
<strong>x</strong><strong>y</strong><strong>z</strong> 

```

pos **xyz** t  
**x**** y ****z**  
questio **xyz** n

I simply cannot understand why.

--

---

<div class="post-metadata">

**Author:** ![concept47](https://avatars.discourse-cdn.com/v4/letter/c/f6c823/32.png) [@concept47](https://discuss.elastic.co/u/concept47)\
**Post date:** [December 13, 2012, 1:51am UTC](https://discuss.elastic.co/t/elasticsearch-highlighting-on-ngram-filter-is-wrwong-if-min-gram-is-set-to-1/10059/2 "2012-12-13T01:51:17Z")

</div>

using Elasticsearch 19.2 btw, also want to point out that if I change from  
using nGram to EdgeNGram (everything else exactly the same) with min\_gram  
set to 1 then it works just fine.

--

---

<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:** [July 6, 2017, 3:00am UTC](https://discuss.elastic.co/t/elasticsearch-highlighting-on-ngram-filter-is-wrwong-if-min-gram-is-set-to-1/10059/3 "2017-07-06T03:00:02Z")

</div>