# Potential Clash of Auto-Generated IDs

**URL:** <https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738>\
**Category:** Elasticsearch\
**Created:** [February 7, 2018, 2:00am UTC](https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738 "2018-02-07T02:00:33Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![krmathieu](https://avatars.discourse-cdn.com/v4/letter/k/b5e925/32.png) [@krmathieu](https://discuss.elastic.co/u/krmathieu)\
**Post date:** [February 7, 2018, 2:00am UTC](https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738/1 "2018-02-07T02:00:33Z")

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I am going to be processing a couple million records of the same type into separate indexes for now and will be allowing ES to auto assign the ID of the records. My question is, if I do that and then later decide to merge them all into one index is there any possibility that some records will fail to merge into the new index because of a clash with an auto generated ID in another index? Any info would be appreciated. Thanks.

Kevin

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**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:** [February 7, 2018, 3:05am UTC](https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738/2 "2018-02-07T03:05:12Z")

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There is a possibility, though I'd imagine it'd be pretty small.

From [Indexing a Document | Elasticsearch: The Definitive Guide [2.x] | Elastic](https://www.elastic.co/guide/en/elasticsearch/guide/current/index-doc.html#_autogenerating_ids);

> Autogenerated IDs are 20 character long, URL-safe, Base64-encoded GUID strings. These GUIDs are generated from a modified FlakeID scheme which allows multiple nodes to be generating unique IDs in parallel with essentially zero chance of collision.

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**Author:** ![krmathieu](https://avatars.discourse-cdn.com/v4/letter/k/b5e925/32.png) [@krmathieu](https://discuss.elastic.co/u/krmathieu)\
**Post date:** [February 8, 2018, 3:21am UTC](https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738/3 "2018-02-08T03:21:39Z")

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@warkolm thank you very much for the info, exactly what I was looking for!

Kevin

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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:** [March 8, 2018, 3:22am UTC](https://discuss.elastic.co/t/potential-clash-of-auto-generated-ids/118738/4 "2018-03-08T03:22:07Z")

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