# Default Similarity Model for a Index
**URL:** https://discuss.elastic.co/t/default-similarity-model-for-a-index/44091
**Category:** Elasticsearch
**Created:** [March 10, 2016, 10:34pm UTC](https://discuss.elastic.co/t/default-similarity-model-for-a-index/44091 "2016-03-10T22:34:48Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@Shiv\_Naidu](https://discuss.elastic.co/u/Shiv_Naidu)
#### Post date: [March 10, 2016, 10:34pm UTC](https://discuss.elastic.co/t/default-similarity-model-for-a-index/44091/1 "2016-03-10T22:34:48Z")
I am trying to figure out if I can configure the similarity model like BM25 as default for just a index in my Elastic installation.
I found that I can add a configuration setting for the whole Index in the YAML file like this, "index.similarity.default.type: BM25", but I want to configure it for a single Index. For example, I have 4 indexes currently,
1. Customer1
2. Customer2
3. Customer3
4. Customer4
All the above use the default similarity type. but for new Index "Customer5" I want to change the similarity to use "BM25". I know that I can set a custom one and give it for the fields that I want to use this similarity as mentioned in this [document](https://www.elastic.co/guide/en/elasticsearch/guide/current/changing-similarities.html). But that is too cumbersome and with dynamic data it doesn't work well.
I am not sure how to satisfy my requirement b/c I couldn't find a document or discussion in the group. Please let me know if there is a way.
Thanks,
-Shiv
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [July 5, 2017, 11:09pm UTC](https://discuss.elastic.co/t/default-similarity-model-for-a-index/44091/2 "2017-07-05T23:09:19Z")