Upgrade to Lucene 4.9
Lucene Change Log
New Terms.getMin/Max methods to retrieve the lowest and highest terms per field.
New IDVersionPostingsFormat, optimized for ID lookups that associate a monotonically increasing version per ID.
Atomic update of a set of doc values fields.
Numerous optimizations for doc values search-time performance.
New (default) Lucene49NormsFormat to better compress certain cases such as very short fields.
New SORTED_NUMERIC docvalues type for efficient processing of multi-valued numeric fields.
Indexer passes previous token stream for easier reuse.
MoreLikeThis accepts multiple values per field.
All classes that estimate their RAM usage now implement a new Accountable interface.
Lucene files are now written by (File)OutputStream on all platforms, completely disallowing seeking with simplified IO APIs.
Improve the confusing error message when MMapDirectory cannot create a new map.
Especially, the spatial module integrated with spatial4j.