The 3.4.1 release introduces a compatibility package for running newer versions
in Apache Solr 1.4.x and fixes an issue with clustering quality in Java
and C# API and a number of other minor problems.
Updated clustering for Apache Solr 1.4.x.
Solr 1.4.x comes with built-in search results clustering based on version 3.1.0 of Carrot2.
Newer versions of Carrot2 can now be used with Solr 1.4.x through the
compatibility package this release provides. Please
see Carrot2 manual for installation instructions.
Fix for degraded clustering quality in Java and C# API
The default configurations of version 3.4.0 of Carrot2 Java
and C# API perform clustering without stemming, which
may lead to degraded clustering quality. A drop-in upgrade from an
earlier release to release 3.4.0 of Carrot2 JAR would also result in
a similar clustering quality decrease.
Release 3.4.1 addresses this issue: Java and C# API perform
clustering using the appropriate stemming engine, a drop-in upgrade
of the Carrot2 JAR does not cause the clustering quality decrease.
Other tools, including Carrot2 Document Clustering Workbench,
Carrot2 Document Clustering Server, Carrot2 Command Line Interface,
Carrot2 Web Application and the Solr clustering component were not
affected by this issue. For more details and a workaround for
Carrot2 1.4.0, please see CARROT-723.
For a complete list of improvements and bug fixes, see JIRA
issues fixed in version 3.4.1. For more new features, please see release 3.4.0 and release 3.3.0 notes.