# Detect duplicates of \_id

**URL:** <https://discuss.elastic.co/t/detect-duplicates-of-id/175519>\
**Category:** Elasticsearch\
**Created:** [April 5, 2019, 5:50am UTC](https://discuss.elastic.co/t/detect-duplicates-of-id/175519 "2019-04-05T05:50:53Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Hiroki\_Otsuka](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/hiroki_otsuka/32/43482_2.png) [@Hiroki\_Otsuka](https://discuss.elastic.co/u/Hiroki_Otsuka)\
**Post date:** [April 5, 2019, 5:50am UTC](https://discuss.elastic.co/t/detect-duplicates-of-id/175519/1 "2019-04-05T05:50:53Z")

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I use two indexes.

The two indexes contain the same \_id by the program.  
For example, IndexA has "\_id 777", and also indexB has "\_id 777".

I want to output the same \_id in something nested form like collapse, when I search in all indexes.  
like this  
[https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-collapse.html](https://www.elastic.co/guide/en/elasticsearch/reference/current/search-request-collapse.html)

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**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:** [April 5, 2019, 6:14am UTC](https://discuss.elastic.co/t/detect-duplicates-of-id/175519/2 "2019-04-05T06:14:01Z")

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You can't join indices.

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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:** [May 3, 2019, 6:14am UTC](https://discuss.elastic.co/t/detect-duplicates-of-id/175519/3 "2019-05-03T06:14:10Z")

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