# Index alias

**URL:** <https://discuss.elastic.co/t/index-alias/292829>\
**Category:** Elasticsearch\
**Tags:** ilm-index-lifecycle-management\
**Created:** [December 23, 2021, 3:49pm UTC](https://discuss.elastic.co/t/index-alias/292829 "2021-12-23T15:49:58Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![iamtheschmitzer](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/iamtheschmitzer/32/96988_2.png) [@iamtheschmitzer](https://discuss.elastic.co/u/iamtheschmitzer)\
**Post date:** [December 23, 2021, 3:49pm UTC](https://discuss.elastic.co/t/index-alias/292829/1 "2021-12-23T15:49:58Z")

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If I have a rollover index `foo-000001`, which rolls over to `foo-N` and alias index `foo` for them, is `foo` equivalent to the "latest" of those rollovers or the "union" of them?

Thanks

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**Author:** ![elasticforme](https://avatars.discourse-cdn.com/v4/letter/e/f05b48/32.png) [@elasticforme](https://discuss.elastic.co/u/elasticforme)\
**Post date:** [December 23, 2021, 4:13pm UTC](https://discuss.elastic.co/t/index-alias/292829/2 "2021-12-23T16:13:03Z")

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alias always point to latest one. (in order to write to only one index)  
index pattern point to union of all ( in order to see all data)

foo -\> foo-000x (latest one which writes data on to foo-000x (index alias)

foo-\* -\> foo-\* (and you use that to search all data) (index pattern)

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<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:** [January 20, 2022, 4:13pm UTC](https://discuss.elastic.co/t/index-alias/292829/3 "2022-01-20T16:13:55Z")

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