This is a copy of the release announcement:
The Lucene PMC is pleased to announce the release of Apache Solr 3.4.0!
Solr's version number was synced with Lucene following the Lucene/Solr merge, so Solr 3.4.0 contains Lucene 3.4.0.
If you are already using Apache Solr 3.1, 3.2 or 3.3, we strongly recommend you upgrade to 3.4.0 because of the index corruption bug on OS or computer crash or power loss (LUCENE-3418), now fixed in 3.4.0.
Solr 3.4.0 release highlights include
- Bug fixes and improvements from Apache Lucene 3.4.0, including a major bug (LUCENE-3418) whereby a Lucene index could easily become corrupted if the OS or computer crashed or lost power.
- SolrJ client can now parse grouped and range facets results (SOLR-2523).
A new XsltUpdateRequestHandler allows posting XML that's transformed by a provided XSLT into a valid Solr document (SOLR-2630).
- Post-group faceting option (group.truncate) can now compute facet counts for only the highest ranking documents per-group. (SOLR-2665).
- Add commitWithin update request parameter to all update handlers that were previously missing it. This tells Solr to commit the change within the specified amount of time (SOLR-2540).
- You can now specify NIOFSDirectory (SOLR-2670).
New parameter hl.phraseLimit speeds up FastVectorHighlighter (LUCENE-3234).
- The query cache and filter cache can now be disabled per request. See this wiki page (SOLR-2429).
Improved memory usage, build time, and performance of SynonymFilterFactory (LUCENE-3233).
- Added omitPositions to the schema, so you can omit position information while still indexing term frequencies (LUCENE-2048).
Various fixes for multi-threaded DataImportHandler.
See the release notes for a more complete list of all the new features, improvements, and bugfixes.