# Elasticsearch Configuring \_id autogeneration function

**URL:** <https://discuss.elastic.co/t/elasticsearch-configuring-id-autogeneration-function/189816>\
**Category:** Elasticsearch\
**Created:** [July 10, 2019, 3:41pm UTC](https://discuss.elastic.co/t/elasticsearch-configuring-id-autogeneration-function/189816 "2019-07-10T15:41:27Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![orchapod](https://avatars.discourse-cdn.com/v4/letter/o/97f17d/32.png) [@orchapod](https://discuss.elastic.co/u/orchapod)\
**Post date:** [July 10, 2019, 3:41pm UTC](https://discuss.elastic.co/t/elasticsearch-configuring-id-autogeneration-function/189816/1 "2019-07-10T15:41:27Z")

</div>

I understand that when you attempt to index an document without specifying an id, Elasticsearch will autogenerate an unique id for your document.

I am wondering if it's possible to configure that id generation function for an existing index? I am hoping that so I can customize the id generation such as attaching a prefix, restricting character rules (like no numbers or hyphens), or use autoincrementing integers instead of strings.

I'd rather avoid using explicit id definition as the documentation explains that inserting a document with explicit id is slower than without explicit id because Elasticsearch would have to look through the index to find existing document with same id to replace.

I imagine that it could be done with `_mappings` configuration to an index with generator function as a painless script.

---

<div class="post-metadata">

**Author:** ![Christian\_Dahlqvist](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/christian_dahlqvist/32/4617_2.png) [@Christian\_Dahlqvist](https://discuss.elastic.co/u/Christian_Dahlqvist)\
**Post date:** [July 10, 2019, 4:37pm UTC](https://discuss.elastic.co/t/elasticsearch-configuring-id-autogeneration-function/189816/2 "2019-07-10T16:37:57Z")

</div>

No, that is not configurable.

---

<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 7, 2019, 4:40pm UTC](https://discuss.elastic.co/t/elasticsearch-configuring-id-autogeneration-function/189816/3 "2019-08-07T16:40:02Z")

</div>

This topic was automatically closed 28 days after the last reply. New replies are no longer allowed.