# Multiple documents with same \_id
**URL:** https://discuss.elastic.co/t/multiple-documents-with-same-id/108567
**Category:** Elasticsearch
**Created:** [November 21, 2017, 1:32pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567 "2017-11-21T13:32:32Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@pokaleshrey](https://discuss.elastic.co/u/pokaleshrey)
#### Post date: [November 21, 2017, 1:32pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/1 "2017-11-21T13:32:32Z")
Hi,
I am using single master, 2 data nodes for my cluster. (6shards, 1Replica)
I also have routing specified while indexing documents.
When i have indexed about 20Gb of documents, i can see multiple documents with same \_ID 🙄
Can this happen ? As i assume that ID are unique, and even if we create many document with same ID but different content it should overwrite it and increment the \_version.
Please help !!
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### Author:  [@jpountz](https://discuss.elastic.co/u/jpountz)
#### Post date: [November 21, 2017, 1:34pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/2 "2017-11-21T13:34:35Z")
This is either a bug in Elasticsearch or you indexed two documents with the same `_id` but different routing values.
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### Author:  [@pokaleshrey](https://discuss.elastic.co/u/pokaleshrey)
#### Post date: [November 21, 2017, 1:37pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/3 "2017-11-21T13:37:44Z")
The later case is true.
I have indexed two documents with same \_id but different value.
But, i thought ES keeps the \_id unique per index. So even if the routing value is different the index is the same.
Can you please put some light on above assumption ?
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### Author:  [@Mark\_Harwood](https://discuss.elastic.co/u/Mark_Harwood)
#### Post date: [November 21, 2017, 1:42pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/4 "2017-11-21T13:42:51Z")
From [the docs:](https://www.elastic.co/guide/en/elasticsearch/reference/5.5/mapping-routing-field.html#_unique_ids_with_custom_routing)
> When indexing documents specifying a custom \_routing, the uniqueness of the \_id is not guaranteed across all of the shards in the index. In fact, documents with the same \_id might end up on different shards if indexed with different \_routing values.
> It is up to the user to ensure that IDs are unique across the index.
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### Author:  [@pokaleshrey](https://discuss.elastic.co/u/pokaleshrey)
#### Post date: [November 21, 2017, 1:45pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/5 "2017-11-21T13:45:08Z")
Thanks mark. I would rethink of the strategy now 🙃
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### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [December 19, 2017, 1:45pm UTC](https://discuss.elastic.co/t/multiple-documents-with-same-id/108567/6 "2017-12-19T13:45:16Z")
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