Lucene and Solr 6.4

It is a pleasure to inform that the new version, a first release of 2017, of Lucene library and Solr search server has been released. It is another release from the 6.x branch and it is numbered 6.4. Release fixes a few bugs found in the earlier version of Lucene and Solr and brings new functionalities as well.

Example changes in the Lucene library:

  • New similarity called BooleanSimilarity have been introduced that gives terms a score equal to their query boost
  • New token filter called SynonymGraphFilter have been introduced for multi-token query time synonyms and token streams produced by that filter is correctly handled by queries
  • Index sorting is supported on multi-valued fields

Example changes in Solr search engine:

  • Ability to prioritize streaming expressions
  • Command line tool to manage snapshot functionality
  • Key store for SSL can be specified in file
  • Ability to use the new Unified Highlighter by using hl.method=unified
  • Reworked metrics and introduction of Metrics API
  • Introduction of maxRamMB to control memory consumed by FastLRUCache
  • Introduction of SkipExistingDocumentProcessor for skipping update and indexing of existing documents
  • New configuration flag enable, which allows enabling and disabling of any cache type

Full list of changes can be found at the following URL: and

Apache Lucene library 6.4 can be downloaded from: If you want to download Solr search server 6.4 go to

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