Upgrade Notes:

• Upgrading from 0.18 requires issuing a full flush of all the indices in the cluster (curl host:9200/_flush) before shutting down the cluster, with no indexing operations happening after the flush.
• The local gateway state structure has changed from 0.18, a backup of the state files is created when upgrading, they can then be used to downgrade back to 0.18. Don’t downgrade without using them.

Breaking changes:

• Introduce Text abstraction, allowing for improved representation of strings, apply to HighlightedField (breaks backward for Java API from String to Text) (#2093)
• Stored binary fields to change internal representation (break Java API if used) (#2092)

New features:

• Explain API (#2184)
• Multi match query (#2153)
• Cluster Nodes hot_threads API (#2134)
• Compression: Support snappy as a compression option (#2081)

Enhancements:

• Reduce index.shard.recovery.concurrent_streams from 5 to 3 to reduce the load when doing recovery (#2198)
• Upgrade to netty 3.5.5 (#2196)
• MinimumNumberShouldMatch inconcistency (#2194)
• Upgrade to Netty 3.5.4 (#2180)
• Rename text query to match query (text query still works, with variants) (#2150)
• word_delimiter token filter does not honor “type_table” option. (#2145)
• Improve recovery time when processing large mappings (#2138)
• Increase default recovery chunk size (#2125)
• Upgrade to Netty 3.5.3 (#2119)
• ShingleTokenFilterFactory doesn’t expose all relevant settings (#2116)
• Upgrade to Lucene 3.6.1 (#2110)
• Upgrade to Netty 3.5.2 (#2084)
• All Field: Automatically detect when field level boosting is used, and optimize when its not (#2189)
• Mapping:
  • String type to allow for a “ignore_above” size parameter, above which it will ignore the content (#2121)
  • Numeric/Date types to have a flag to ignore wrongly formatted values (#2120)
• Node Stats: Add jvm buffer pools stats (when available, for java 7 and above) (#2122)
• Thread Pool: Allow to configure the queue_type for fixed thread pool (linked/array), defaults to array (#2086)
• Transport/Http: Remove explicit setting of send/receive buffer, and improve netty receive buffer predictor (#2124)

Bug fixes:

• Incorrect application of boost in SpanNotQueryBuilder (#2192)
• Date Histogram facet fails with “pre_zone” : “+02:00” (#2141)
• Local Gateway: old global state files are not properly deleted (#2085)
• Update API: Update through an alias with routing configured on it fail to use the routing (#2155)