SolrJ versions backward/forward compability with Solr server versions

[Masseau Olivier <Ol...@inetum.com.INVALID>]

Hello,

I've read this but I don't know if it is still true :
https://cwiki.apache.org/confluence/display/solr/solrj


Our goal is to have our Java application which is using SolrJ, to be compatible with both Solr 7 and Solr 8 (as some of our clients want to use Solr 8 and some are still not prepared to migrate).

- Is SolrJ 7 compatible with both Solr 7 and a Solr 8 ?
- In case it may note be, maybe is SolrJ 8 compatible with both Solr 7 and a Solr 8 ?

Is there somewhere an eventual compatibility matrix ?

Thanks a lot ;)

Re: SolrJ versions backward/forward compability with Solr server versions

[Shawn Heisey <ap...@elyograg.org>]

On 3/13/23 09:46, Masseau Olivier wrote:
> I've read this but I don't know if it is still true :
> https://cwiki.apache.org/confluence/display/solr/solrj
> 
> Our goal is to have our Java application which is using SolrJ, to be compatible with both Solr 7 and Solr 8 (as some of our clients want to use Solr 8 and some are still not prepared to migrate).

If you're using the http clients, there should be good compatibility 
across a wide range of versions.  I've seen people using SolrJ 4.x with 
8.x or 9.x servers and have everything work, and vice versa.  This will 
only work if the solrconfig/schema that is upgraded from the earlier 
version is nearly identical in function, so the same HTTP requests are 
compatible with the config.

If you're using the Cloud client, the situation is far more murky.  This 
is because the client doesn't just send HTTP requests, it interacts 
directly with zookeeper and is tightly integrated with the SolrCloud 
cluster.  I personally would want Solr and SolrJ to be in the same major 
version in that situation, and I would strive to make them the EXACT 
same version if possible.

That page you linked should be updated with better SolrCloud info.  I 
can tell by reading it that it's VERY old, written before 5.0 was released.

Thanks,
Shawn