We are using Elastic stack version 8.9 currently and Java api client 7.17. we want to upgrade to 9.x. From 8.9 we are migrating to 8.18 or 8.19, then from 8.19 version to 9.x. How should we upgrade java client?
Have you looked at the official documentation?
The Java 7.17 client should work with all 8.x versions as long as it is in compatibility mode, but is not guaranteed to work with Elasticsearch 9.x. I would therefore recommend following the flow in the official documentation and upgrade to Elasticsearch 8.19 before upgrading the client to the latest 8.x version as well. Once that is done you should be able to migrate to Elasticsearch 9.x as the 8.x client will work with this in compatibility mode.
Thanks for your quick response Christian. But I see that HLRC was deprecated in 7.15 and frozen on 7.17. So, Should we upgrade server to 8.19 first and migrate java HLRC 7.17 to java API client 8.x and then upgrade server to 9.x?
Yes, you will need to switch to the new Java client before going to Elasticsearch 9.x.