Release Notes: The ability to group search results was added. The IndexUpgrader tool was added. Near-realtime improvements were made. Document block indexing was implemented. Bugs were fixed.
Release Notes: Disk-based doc values and improved filter caching.
Release Notes: This release adds 12 bugfixes and an optimization, including fixes for a serious bug which could cause deadlocks.
Release Notes: A bugfix release for 3.6.0.
Release Notes: This release improves auto-suggest, adds Japanese analysis, and improves "join".
Release Notes: This release adds suggest/autocomplete functionality. It adds support for merging results from different shards (distributed search). There are improvements to result grouping, near-real-time, and index merging. Improved stemming capabilities.