Lucene is an Open Source, mature and high-performance Java search engine. It is highly flexible, and scalable from hundreds to millions of documents.

Luke is a handy development and diagnostic tool, which accesses already existing Lucene indexes and allows you to display and modify their content in several ways:

• browse by document number, or by term
• view documents / copy to clipboard
• retrieve a ranked list of most frequent terms
• execute a search, and browse the results
• analyze search results
• selectively delete documents from the index
• reconstruct the original document fields, edit them and re-insert to the index
• optimize indexes
• open indexes consisting of multiple parts, and/or located on Hadoop filesystem
• and much more...

Current stable release of Luke is 4.0.0-ALPHA and it includes Lucene 4.0.0-ALPHA and Hadoop 0.20.2. Available is also Luke 3.5.0 (using Lucene 3.5.0), Luke 1.0.1 (using Lucene 3.0.1), 0.9.9.1 based on Lucene 2.9.1, and other versions as well - please see the Downloads section.

Luke releases are numbered the same as the version of Lucene libraries that they use (plus a minor number in case of bugfix releases).

Below is a screenshot of the application showing the Overview section, which displays the details of the index format and some overall statistics.

Luke Overview Tab