# Is index creation API atomic? **URL:** \ **Category:** Elasticsearch\ **Created:** [July 10, 2019, 10:07pm UTC](https://discuss.elastic.co/t/is-index-creation-api-atomic/189881 "2019-07-10T22:07:09Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Anfernee\_Xu](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/anfernee_xu/32/45644_2.png) [@Anfernee\_Xu](https://discuss.elastic.co/u/Anfernee_Xu)\ **Post date:** [July 10, 2019, 10:07pm UTC](https://discuss.elastic.co/t/is-index-creation-api-atomic/189881/1 "2019-07-10T22:07:09Z")
Is index creation API atomic? As I might have multiple clients trying to create the same index at the same time, can I assume index creation is atomic which mimic POSIX file system? ---
**Author:** ![Bernt\_Rostad](https://avatars.discourse-cdn.com/v4/letter/b/3ab097/32.png) [@Bernt\_Rostad](https://discuss.elastic.co/u/Bernt_Rostad)\ **Post date:** [July 11, 2019, 5:01am UTC](https://discuss.elastic.co/t/is-index-creation-api-atomic/189881/2 "2019-07-11T05:01:54Z")
> [@Anfernee\_Xu](#): > > As I might have multiple clients trying to create the same index at the same time, can I assume index creation is atomic In a way it is atomic, since the new index must be added to the [cluster state](https://www.elastic.co/guide/en/elasticsearch/reference/current/cluster-state.html) which is controlled by the master node. Even if multiple requests are trying to add a new index to the cluster, only the first one handled by the master node will succeed - all the other requests will fail and return a "resource\_already\_exists\_exception" to the clients. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [August 8, 2019, 5:02am UTC](https://discuss.elastic.co/t/is-index-creation-api-atomic/189881/3 "2019-08-08T05:02:02Z")
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