# Post Upgrade - To REINDEX or not to REINDEX

**URL:** <https://discuss.elastic.co/t/post-upgrade-to-reindex-or-not-to-reindex/359179>\
**Category:** Elasticsearch\
**Tags:** reindex\
**Created:** [May 9, 2024, 12:26pm UTC](https://discuss.elastic.co/t/post-upgrade-to-reindex-or-not-to-reindex/359179 "2024-05-09T12:26:57Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![peledc](https://avatars.discourse-cdn.com/v4/letter/p/e79b87/32.png) [@peledc](https://discuss.elastic.co/u/peledc)\
**Post date:** [May 9, 2024, 12:26pm UTC](https://discuss.elastic.co/t/post-upgrade-to-reindex-or-not-to-reindex/359179/1 "2024-05-09T12:26:57Z")

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This is more of general "Best Practice" question:

We have a 1TB of data in our ES7 indices.  
We intend to upgrade it to version 8.xx

Question is - Should we REINDEX existing indices (which were created in version 7.xx) ?  
We understand this is not mandatory but  
may we encounter any features which may not be available if indices are not reindexed to version 8.xx?