# BM25 score of two indexed document in elasticsearch **URL:** \ **Category:** Elasticsearch\ **Created:** [January 27, 2018, 8:30am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289 "2018-01-27T08:30:53Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Saeed\_Zhiany](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saeed_zhiany/32/12865_2.png) [@Saeed\_Zhiany](https://discuss.elastic.co/u/Saeed_Zhiany)\ **Post date:** [January 27, 2018, 8:30am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/1 "2018-01-27T08:30:53Z")
I have an index with two type t1 and t2. a few documents has been index in each of them with following structure: ``` { "mappings": { "t1": { "properties": { "body": { "type": "string" } } }, "t2": { "properties": { "body": { "type": "string" } } } } } ``` how can I obtain BM25 score between two arbitrary documents D1 and D2. please note that I don't want to find Documents similar to D1 or D2. so I think more\_like\_this query is not proper for my case. ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [January 27, 2018, 8:42am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/2 "2018-01-27T08:42:47Z")
Note that multiple types is not allowed anymore in 6.x. ---
**Author:** ![Saeed\_Zhiany](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saeed_zhiany/32/12865_2.png) [@Saeed\_Zhiany](https://discuss.elastic.co/u/Saeed_Zhiany)\ **Post date:** [January 27, 2018, 8:54am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/3 "2018-01-27T08:54:41Z")
I don't knew that, thank you! but it is not important right now, because as you see structure of documents are same. I can store my documents in one type. are you have any solution for main problem? ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [January 27, 2018, 9:10am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/4 "2018-01-27T09:10:17Z")
You can just obtain individual scores and compare on client side I think. What do you want to do with that score exactly? ---
**Author:** ![Saeed\_Zhiany](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saeed_zhiany/32/12865_2.png) [@Saeed\_Zhiany](https://discuss.elastic.co/u/Saeed_Zhiany)\ **Post date:** [January 27, 2018, 9:14am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/5 "2018-01-27T09:14:40Z")
how can I do that?! BM25 has been defined as a score between a Query and a document, such that the query can be a document itself. am I right? I want use this score as a feature for a learning to rank application. ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [January 27, 2018, 10:47am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/6 "2018-01-27T10:47:35Z")
You mean getting a score when there is no query? I don't know. May be others have ideas. If you extract all the values you have in document A then build a bool query with should clauses for each field, may be you can call [https://www.elastic.co/guide/en/elasticsearch/reference/6.1/search-explain.html](https://www.elastic.co/guide/en/elasticsearch/reference/6.1/search-explain.html) and get that? But I'm unsure here if it would help. ---
**Author:** ![Saeed\_Zhiany](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saeed_zhiany/32/12865_2.png) [@Saeed\_Zhiany](https://discuss.elastic.co/u/Saeed_Zhiany)\ **Post date:** [January 27, 2018, 10:58am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/7 "2018-01-27T10:58:28Z")
"You mean getting a score when there is no query?" exactly, The original BM25 formula can be used to calculate the score between each arbitrary documents. (query also can be consider as a document) "If you extract all the values you have in document A then build a bool query with should clauses for each field, may be you can call [https://www.elastic.co/guide/en/elasticsearch/reference/6.1/search-explain.html](https://www.elastic.co/guide/en/elasticsearch/reference/6.1/search-explain.html) and get that?" I don't think this is works. because the formula is a sum of aggregated weight on common words between two documents. I can write a code that calculate this score. it's not hard, but I thought may be it's implemented in elasticsearch in optimal way. ---
**Author:** ![dadoonet](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dadoonet/32/137187_2.png) [@dadoonet](https://discuss.elastic.co/u/dadoonet)\ **Post date:** [January 27, 2018, 10:59am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/8 "2018-01-27T10:59:58Z")
I dunno. @jimczi or @jpountz might have ideas? ---
**Author:** ![Saeed\_Zhiany](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/saeed_zhiany/32/12865_2.png) [@Saeed\_Zhiany](https://discuss.elastic.co/u/Saeed_Zhiany)\ **Post date:** [January 28, 2018, 5:53am UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/9 "2018-01-28T05:53:07Z")
for calculating BM25 by myself, I need length of document and average document length on whole documents in collection. according to formula, length of a document is number of it's word. I search a lot, but no success to find a way to elastic return this values to me. could you please give me a solution? ---
**Author:** ![jpountz](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/jpountz/32/45836_2.png) [@jpountz](https://discuss.elastic.co/u/jpountz)\ **Post date:** [February 1, 2018, 2:25pm UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/10 "2018-02-01T14:25:12Z")
There is no built-in way to do this. One way would be to build a giant disjunction out of D1 and run it against D2. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [March 1, 2018, 2:25pm UTC](https://discuss.elastic.co/t/bm25-score-of-two-indexed-document-in-elasticsearch/117289/11 "2018-03-01T14:25:18Z")
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