# Latent Semantic Indexing in Elastic search

**URL:** https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245
**Category:** Elasticsearch
**Created:** [July 7, 2017, 9:35am UTC](https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245 "2017-07-07T09:35:17Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![gurdeep](https://avatars.discourse-cdn.com/v4/letter/g/85f322/32.png) [@gurdeep](https://discuss.elastic.co/u/gurdeep)
#### Post date: [July 7, 2017, 9:35am UTC](https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245/1 "2017-07-07T09:35:17Z")

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Hi,  
I am trying to use "Latent Semantic Indexing " as the custom Similarity Algorithm in Elastic Search. What is the way I can do it? Does elastic Search provide any plugin architecture for this particular Algorithm?

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### Author: ![Arun\_Ramachandran](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/arun_ramachandran/32/19736_2.png) [@Arun\_Ramachandran](https://discuss.elastic.co/u/Arun_Ramachandran)
#### Post date: [July 7, 2017, 11:05am UTC](https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245/2 "2017-07-07T11:05:33Z")

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Hi Elastic team,

I'm having the similar requirement, but not finding a way how to accommodate it.  
Is the ranking module is pluggable?

Thanks,  
Arun Ramachandran.

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### Author: ![jimczi](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jimczi/32/47985_2.png) [@jimczi](https://discuss.elastic.co/u/jimczi)
#### Post date: [July 7, 2017, 12:45pm UTC](https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245/3 "2017-07-07T12:45:12Z")

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By default several similarities are available:  
[https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules-similarity.html#\_available\_similarities](https://www.elastic.co/guide/en/elasticsearch/reference/current/index-modules-similarity.html#_available_similarities)

If you want a new one, you need to write a plugin that defines your custom similarities. Though latent semantic indexing requires a lot of additional structures to score a document so you'll need to build these infos outside of ES and find a way to make them available in your similarity.

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### Author: ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)
#### Post date: [August 4, 2017, 12:45pm UTC](https://discuss.elastic.co/t/latent-semantic-indexing-in-elastic-search/92245/4 "2017-08-04T12:45:32Z")

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