Upgrading elastic7 to elastic8 no reindexing required?

Question

I just did a test upgrade from elastic 7.17.11 to 8.8.2 and was able to use my old indices and write to them without reindexing to a new index. The only information I found was upgrading from 5.x or 6.x to 8 - but nothing is stating required steps to upgrade from 7.17.x to 8.x.

Is reindexing no more required? What happens when upgrading to some future 9.x? Will I have to reindex

• before going to 9
• after going to 9
• or not at all?

Answer 1

It's stated in the official documentation

To upgrade to 8.8.2 from 7.16 or an earlier version, you must first upgrade to 7.17

and also in the upgrade guide:

To upgrade to 8.8.2 from 7.16 or earlier, you must first upgrade to 7.17. This enables you to use the Upgrade Assistant to identify and resolve issues, reindex indices created before 7.0, and then perform a rolling upgrade.

So if you're already on 7.17, then you're good to upgrade to 8 without reindexing. You only need to reindex if you have indices created before 7.0

Also worth noting that starting in 8.3, it is now possible to read/search indices created in older versions (5, 6) without reindexing them but with certain conditions.