# Document compression - duplicate fields **URL:** \ **Category:** Elasticsearch\ **Created:** [October 20, 2020, 9:57am UTC](https://discuss.elastic.co/t/document-compression-duplicate-fields/252658 "2020-10-20T09:57:42Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![probson](https://avatars.discourse-cdn.com/v4/letter/p/e47c2d/32.png) [@probson](https://discuss.elastic.co/u/probson)\ **Post date:** [October 20, 2020, 9:57am UTC](https://discuss.elastic.co/t/document-compression-duplicate-fields/252658/1 "2020-10-20T09:57:42Z")
Hi, If i copy fields and rename them to match ECS you have a duplicate of data, are these 2 fields deduplicated as part of the compression within the doc? Looking at the wiki for Thanks Phil ---
**Author:** ![Wolfram\_Haussig](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/wolfram_haussig/32/70528_2.png) [@Wolfram\_Haussig](https://discuss.elastic.co/u/Wolfram_Haussig)\ **Post date:** [October 21, 2020, 11:10am UTC](https://discuss.elastic.co/t/document-compression-duplicate-fields/252658/2 "2020-10-21T11:10:16Z")
Hello Philip, I don't know the answer to your question but you could use field aliases instead of duplicating the field: [https://www.elastic.co/guide/en/elasticsearch/reference/master/alias.html](https://www.elastic.co/guide/en/elasticsearch/reference/master/alias.html) This way, the field is stored only once but can still be accessed in both ways. Best regards Wolfram ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [November 18, 2020, 11:10am UTC](https://discuss.elastic.co/t/document-compression-duplicate-fields/252658/3 "2020-11-18T11:10:24Z")
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