# Why is the length of keyword array always 1? **URL:** \ **Category:** Elasticsearch\ **Created:** [March 21, 2023, 12:06pm UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164 "2023-03-21T12:06:38Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![lyq2333](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lyq2333/32/118714_2.png) [@lyq2333](https://discuss.elastic.co/u/lyq2333)\ **Post date:** [March 21, 2023, 12:06pm UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/1 "2023-03-21T12:06:38Z")
I create an index by `PUT my-index-000002 { "mappings": { "properties": { "content":{ "type": "keyword", "index_options": "freqs" }, "id":{ "type": "integer" } } } }` Then I add a doc by `POST my-index-000002/_doc/1 { "content": ["apple","apple"] }` I search the doc by `GET my-index-000002/_search { "query": { "term": { "content": { "value": "apple" } } }, "explain": true }` But the dl in explanation is 1. ![image](https://us1.discourse-cdn.com/elastic/original/3X/c/d/cd0260cabc0f030529f291ff618dd06d959469b0.jpeg) Is it a bug or by design？Can anyone help me？ ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [March 22, 2023, 12:13am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/2 "2023-03-22T00:13:41Z")
Welcome to our community! 😃 And Thanks heaps for providing a replication, it makes it heaps easier to see what you are doing! From [Wrong averageFieldLength(avgdl, average length of field) and fieldLength (dl, length of field) calculation · Issue #46855 · elastic/elasticsearch · GitHub](https://github.com/elastic/elasticsearch/issues/46855#issuecomment-533071569); > `dl` is the field length for the document so the number of terms that it contains, we call it the norm of the field So you've defined `content` as a `keyword`. You've passed in an array, but it's going to treat that array as a single value because of that mapping, and that's what it's reporting back to you. ---
**Author:** ![lyq2333](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lyq2333/32/118714_2.png) [@lyq2333](https://discuss.elastic.co/u/lyq2333)\ **Post date:** [March 22, 2023, 1:01am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/3 "2023-03-22T01:01:57Z")
Thanks a lot！ If the keyword array is treated as a single value, I think the avgdl should be always 1. Could you tell me the reason why the avgdl is 2 in the explanation? Any reply will be greatly appreciated! ---
**Author:** ![warkolm](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/warkolm/32/39224_2.png) [@warkolm](https://discuss.elastic.co/u/warkolm)\ **Post date:** [March 22, 2023, 3:57am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/4 "2023-03-22T03:57:43Z")
Not sure I can help there sorry, I struggled to find that info as it was. Hopefully someone with more knowledge can step in! ---
**Author:** ![lyq2333](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lyq2333/32/118714_2.png) [@lyq2333](https://discuss.elastic.co/u/lyq2333)\ **Post date:** [March 22, 2023, 5:38am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/5 "2023-03-22T05:38:13Z")
Thanks for your help！ 😃 Anyone else have any ideas? Many Thanks！ ---
**Author:** ![William\_Brafford](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/william_brafford/32/51559_2.png) [@William\_Brafford](https://discuss.elastic.co/u/William_Brafford)\ **Post date:** [March 22, 2023, 1:40pm UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/6 "2023-03-22T13:40:52Z")
I think it's by design. Among the [keyword field parameters](https://www.elastic.co/guide/en/elasticsearch/reference/8.6/keyword.html#keyword-params) is `norms`, which controls "whether field-length should be taken into account when scoring queries." The default is `false`. If I set it to "true" in the mapping definition, I see the expected result. Here's the mapping: ```auto PUT my-index-000002 { "mappings": { "properties": { "content": { "type": "keyword", "index_options": "freqs", "norms": true }, "id": { "type": "integer" } } } } ``` Note that the formula in the explanation is `tf, computed as freq / (freq + k1 * (1 - b + b * dl / avgdl))`. Scoring `dl` as `1.0` makes it do nothing in the formula; I would expect to see it as `1.0` for any keyword field score when `norms` is disabled. Let me know if this works for you. (You'll have to delete and recreate the index, or test on a new one.) The trade-off for `norms`, according to [the docs](https://www.elastic.co/guide/en/elasticsearch/reference/8.6/norms.html), is that the index will require more disk space. ---
**Author:** ![lyq2333](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/lyq2333/32/118714_2.png) [@lyq2333](https://discuss.elastic.co/u/lyq2333)\ **Post date:** [March 23, 2023, 12:56am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/7 "2023-03-23T00:56:28Z")
Thanks! It works for me. 😃 ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [April 20, 2023, 12:56am UTC](https://discuss.elastic.co/t/why-is-the-length-of-keyword-array-always-1/328164/8 "2023-04-20T00:56:59Z")
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