# Add new field which content copied from another one

**URL:** <https://discuss.elastic.co/t/add-new-field-which-content-copied-from-another-one/67250>\
**Category:** Elasticsearch\
**Created:** [November 26, 2016, 11:03pm UTC](https://discuss.elastic.co/t/add-new-field-which-content-copied-from-another-one/67250 "2016-11-26T23:03:50Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![TonyIT](https://avatars.discourse-cdn.com/v4/letter/t/a587f6/32.png) [@TonyIT](https://discuss.elastic.co/u/TonyIT)\
**Post date:** [November 26, 2016, 11:03pm UTC](https://discuss.elastic.co/t/add-new-field-which-content-copied-from-another-one/67250/1 "2016-11-26T23:03:50Z")

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Hi to all!

There is a way to update mapping of my index, with a new field where it's content come from another existing one?  
This because i've to update all documents in my index and i don't wont to lose a specific field declared as "excluded" in \_source.

Thanks!

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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:** [December 24, 2016, 11:04pm UTC](https://discuss.elastic.co/t/add-new-field-which-content-copied-from-another-one/67250/2 "2016-12-24T23:04:06Z")

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