Lucene Features:
- The spellchecker module now includes suggest/auto-complete functionality, with three implementations: Jaspell, Ternary Trie, and Finite State.
- Support for merging results from multiple shards, for both “normal” search results (TopDocs.merge) as well as grouped results using the grouping module (SearchGroup.merge, TopGroups.merge).
- An optimized implementation of KStem, a less aggressive stemmer for English.
- Single-pass grouping implementation based on block document indexing.
- Improvements to MMapDirectory (now also the default implementation returned by FSDirectory.open on 64-bit Linux).
- NRTManager simplifies handling near-real-time search with multiple search threads, allowing the application to control which indexing changes must be visible to which search requests.
- TwoPhaseCommitTool facilitates performing a multi-resource two-phased commit, including IndexWriter.
- The default merge policy, TieredMergePolicy, has a new method (set/getReclaimDeletesWeight) to control how aggressively it targets segments with deletions, and is now more aggressive than before by default.
- PKIndexSplitter tool splits an index by a mid-point term.
Solr Features:
- Grouping / Field Collapsing
- A new, automaton-based suggest/autocomplete implementation offering an order of magnitude smaller RAM consumption.
- KStemFilterFactory, an optimized implementation of a less aggressive stemmer for English.
- Solr defaults to a new, more efficient merge policy (TieredMergePolicy). See http://s.apache.org/merging for more information.
- Important bugfixes, including extremely high RAM usage in spellchecking.
- Bugfixes and improvements from Apache Lucene 3.3