The Apache Lucene community has just released Lucene 3.4.0 and Solr 3.4.0.
There are several juicy additions, but also a critical bug fix. It is recommended that all 3.x-using applications upgrade to 3.4 as soon as possible. Here’s the scoop on this fixed bug:
* Fixed a major bug (LUCENE-3418) whereby a Lucene index could easily become corrupted if the OS or computer crashed or lost power.
Lucene 3.4.0 includes: a new faceting module (contrib/facet) for computing facet counts (both hierarchical and non-hierarchical) at search time (LUCENE-3079); a new join module (contrib/join), enabling indexing and searching of nested (parent/child) documents using (LUCENE-3171); ability to now to index documents with term frequencies included but without positions (LUCENE-2048) – previously omitTermFreqAndPositions always omitted both; and a few other improvements.
Solr 3.4.0 includes: Lucene 3.4.0, which fixes the serious bug mentioned above; a new XsltUpdateRequestHandler allows posting XML that’s transformed by a provided XSLT into a valid Solr document (SOLR-2630); field grouping/collapsing: post-group faceting option (group.truncate) can now compute facet counts for only the highest ranking documents per-group (SOLR-2665); The query cache and filter cache can now be disabled per request (SOLR-2429); Improved memory usage, build time, and performance of SynonymFilterFactory (LUCENE-3233); various fixes for multi-threaded DataImportHandler; and a few other improvements.