ES client upgrade to 9.X

Elastic Stack Elasticsearch
1

Our product is currently with
Current ES client version: 7.17.9 - co.elastic.clients:elasticsearch-java 7.17.9 with Java API Client
Current ES server version: 8.14.3 for test automation
Java:17

We are in process of assessing the upgrade of our client from 7.17.9 to 9.X
Some of our customers are in 8.X and they may continue to be on 8 for some time. (they bring in their own ES clusters)

In such a scenario, What is the recommended version of 9.x of client we can upgrade to ?
The upgraded client should not majorly impact, when ES servers of 7.17.9 & above or at least 8.14.3 and above ?
Or is there some other recommendations you have on this regard ?

2

Hi, since the compatibility matrix only supports same-major client/server pairs (9.x↔9.x, 8.x↔8.x) and compat mode only bridges older-client-to-newer-server, I'd recommend staying on the latest 8.x client (8.19.x).

3

Thanks for quicker response. Could you please advise me that 8.x client can connect with 9.x server ?

4

8.x client can connect to a 9.x server. The Java API Client has compatibility mode enabled by default, so no extra configuration is needed on the client side. Just make sure you're on the latest 8.x client version for the best coverage. Ref : https://www.elastic.co/docs/reference/elasticsearch/rest-apis/compatibility