# Custom similarty: get query length within the score function

**URL:** <https://discuss.elastic.co/t/custom-similarty-get-query-length-within-the-score-function/81936>\
**Category:** Elasticsearch\
**Created:** [April 11, 2017, 8:13am UTC](https://discuss.elastic.co/t/custom-similarty-get-query-length-within-the-score-function/81936 "2017-04-11T08:13:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Jimmy\_Oentung](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jimmy_oentung/32/13827_2.png) [@Jimmy\_Oentung](https://discuss.elastic.co/u/Jimmy_Oentung)\
**Post date:** [April 11, 2017, 8:13am UTC](https://discuss.elastic.co/t/custom-similarty-get-query-length-within-the-score-function/81936/1 "2017-04-11T08:13:50Z")

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I'm trying to develop a KL divergence similarities function for elasticsearch 5.1.1.

To do so, i created a KLDivergenceSimilarity.java which extends the LMSimilarity  
see [github link to KLDivergenceSimilarity.java](https://github.com/jimmyoentung/ES-KLDivergenceSimilarity/blob/master/src/main/java/com/github/jimmyoentung/eskldivergencesimilarity/KLDivergenceSimilarity.java)

My question: how can I get the query length?  
for example: if the user submit "heart attack" the query length that i need is 2.

I know there is a maxOverlap which contain the total number of terms in the query, but how can I access it from my score function in KLDivergenceSimilarity.java file?

alternatively, I saw lucene has axiomatic similarity function that accept query length as a setting parameter. If I use such approach, is there anyway that i can change the similarity setting on the fly without closing and reopening my index?

Thank you

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<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:** [May 9, 2017, 8:19am UTC](https://discuss.elastic.co/t/custom-similarty-get-query-length-within-the-score-function/81936/2 "2017-05-09T08:19:13Z")

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Closed on May 9, 2017, 8:19am UTC

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