# Re: Why isn't Elasticsearch using Sha1 for id? **URL:** \ **Category:** Elasticsearch\ **Created:** [July 26, 2011, 10:44pm UTC](https://discuss.elastic.co/t/re-why-isnt-elasticsearch-using-sha1-for-id/4968 "2011-07-26T22:44:24Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Dan\_Pilone](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/dan_pilone/32/3261_2.png) [@Dan\_Pilone](https://discuss.elastic.co/u/Dan_Pilone)\ **Post date:** [July 26, 2011, 10:44pm UTC](https://discuss.elastic.co/t/re-why-isnt-elasticsearch-using-sha1-for-id/4968/1 "2011-07-26T22:44:24Z")
Do you mean SHA1 of the document itself? I'm pretty sure that would be a problem for us as we can have nested documents with identical values. For example, you could have: \ Dan Pilone ... \ If "author" is indexed as a nested document it will need an id which can't just be the SHA1 of the content we provided. Now I suppose if it has the \_parentId as part of the "content" then the SHA1 would be different, but I don't know when/how the parent id is associated with nested docs. -- Dan -- Dan Pilone Managing Partner, Element 84 LLC [www.element84.com](http://www.element84.com) / [dan@element84.com](mailto:dan@element84.com) / 703-622-7370 On Tue, Jul 26, 2011 at 6:25 PM, ajsie [johnny.weng.luu@gmail.com](mailto:johnny.weng.luu@gmail.com) wrote: > CouchDB is using a 40 long characters SHA1 id and they say that the > risk is very minimal. > > I wonder if there is a risk that the id Elastic search auto generates > will collide with another one since it's only 22 characters long. ---
**Author:** ![Paul\_Loy](https://avatars.discourse-cdn.com/v4/letter/p/ad7895/32.png) [@Paul\_Loy](https://discuss.elastic.co/u/Paul_Loy)\ **Post date:** [July 26, 2011, 10:55pm UTC](https://discuss.elastic.co/t/re-why-isnt-elasticsearch-using-sha1-for-id/4968/2 "2011-07-26T22:55:15Z")
You can supply your own ids... On Tue, Jul 26, 2011 at 11:44 PM, Dan Pilone [dan@element84.com](mailto:dan@element84.com) wrote: > Do you mean SHA1 of the document itself? I'm pretty sure that would be a > problem for us as we can have nested documents with identical values. For > example, you could have: > > \ > > Dan > Pilone > > ... > \ > > If "author" is indexed as a nested document it will need an id which can't > just be the SHA1 of the content we provided. Now I suppose if it has the > \_parentId as part of the "content" then the SHA1 would be different, but I > don't know when/how the parent id is associated with nested docs. -- Dan > > -- > Dan Pilone > Managing Partner, Element 84 LLC > [www.element84.com](http://www.element84.com) / [dan@element84.com](mailto:dan@element84.com) / 703-622-7370 > > On Tue, Jul 26, 2011 at 6:25 PM, ajsie [johnny.weng.luu@gmail.com](mailto:johnny.weng.luu@gmail.com) wrote: > > > CouchDB is using a 40 long characters SHA1 id and they say that the > > risk is very minimal. > > > > I wonder if there is a risk that the id Elastic search auto generates > > will collide with another one since it's only 22 characters long. ## -- Paul Loy [paul@keteracel.com](mailto:paul@keteracel.com) [http://uk.linkedin.com/in/paulloy](http://uk.linkedin.com/in/paulloy) ---
**Author:** ![kimchy](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/kimchy/32/44952_2.png) [@kimchy](https://discuss.elastic.co/u/kimchy)\ **Post date:** [July 27, 2011, 4:11am UTC](https://discuss.elastic.co/t/re-why-isnt-elasticsearch-using-sha1-for-id/4968/3 "2011-07-27T04:11:40Z")
The id generated is a type4 UUID (128bit) that is then base64 to reserve space. On Wed, Jul 27, 2011 at 1:25 AM, ajsie [johnny.weng.luu@gmail.com](mailto:johnny.weng.luu@gmail.com) wrote: > CouchDB is using a 40 long characters SHA1 id and they say that the > risk is very minimal. > > I wonder if there is a risk that the id Elastic search auto generates > will collide with another one since it's only 22 characters long. ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 6, 2017, 3:59am UTC](https://discuss.elastic.co/t/re-why-isnt-elasticsearch-using-sha1-for-id/4968/4 "2017-07-06T03:59:11Z")