Solr 7

[Jose Celestino]

Words by Ricardo Branco [Wed, Oct 11, 2017 at 11:00:03AM +0100]:
> Before I go down the route of upgrading our main Solr instance from 6 to 7,
> just checking if anyone is using Solr 7 with Dovecot.

SOLR 7 works ok with dovecot. We did not upgrade but indexed from scratch with
7.0.0.

From our experience:

Make sure that you set the default queryResponseWriter to XML on 
solrconfig.xml:

     <queryResponseWriter name="xml"
                          default="true"
                          class="solr.XMLResponseWriter" />

Because the default response type is now JSON instead of XML and I don't think
dovecot sends a wt=xml to make it explicit.

Also, consider going to 7.0.1 because 7.0.0 could not read indexes from 6.x
versions. As I said we did a reindex so we were unharmed by that bug but just
saw it on the 7.0.1 changelog.