Major Changes from Solr 4 to Solr 5

Highlights of New Features in Solr 5

Some of the major improvements in Solr 5 include:

Ease Of Use

• Improved bin/solr and new bin/post scripts
• New, and restructured, example Config Sets available by default
• SolrJ now has first class support for the Collections API
• Implicit registration of /replication, /get, and /admin/* request handlers

Operational Support

• Scripts to support installing and running Solr as a service on Linux
• Logging improvements:
  • Transaction log replay status is now logged
  • Optional logging of slow requests.
• Config API that supports paramsets for easily configuring Solr parameters for request handlers and editing common solrconfig.xml options.
• New Blob Store API with support for uploading and distributing plugin jars.

SolrCloud & Distributed Requests

• Splitting of clusterstate to per-collection enables scalability improvement in SolrCloud
• Distributed IDF Support
• Option to configure max bandwidth usage by ReplicationHandler

New Search Functionality

• pivot.facet results can now include nested stats.field results constrained by those pivots
• stats.field can be used to generate statistics over the results of arbitrary numeric functions
• A new DateRangeField has been added for indexing date ranges, especially multi-valued ones
• Spatial fields that used to require units=degrees now take distanceUnits=degrees/kilometers miles instead
• MoreLikeThis query parser allows requesting for documents similar to an existing document
• timeAllowed is now used to prematurely terminate requests during query expansion and SolrClient request retry

Solr is Now a Standalone Server

Beginning with Solr 5.0, Solr is no longer distributed as a "war" (Web Application Archive) suitable for deployment in any Servlet Container.  Solr is now distributed as a stand alone java server application, including start and stop scripts for use on Unix and MS-Windows platforms, as well as an installation script for setting up a "production" installation of Solr on *nix platforms managed via /etc/init.d.

The Upgrading a Solr Cluster section of this guide provides detailed steps for existing users to upgrade their clusters regardless of what servlet container they were using with Solr 4.

Index Format

Solr 5 has no support for reading Lucene/Solr 3.x and earlier indexes.  Be sure to run the Lucene IndexUpgrader included with Solr 4.10 if you might still have old 3x formatted segments in your index. Alternatively: fully optimize your index with Solr 4.10 to make sure it consists only of one up-to-date index segment.

solr.xml Format

Solr 4.4 introduced a new format for the solr.xml file, eliminating the need for each <core> to be explicitly listed.  Instead a process known as "Core Discovery" was introduced relying on core.properties files in each SolrCore instance directory.

Solr 5.0 has eliminated all support for the older solr.xml format, and moved entirely to core discovery.  See the Moving to the New solr.xml Format section for more details.

Collections API

Solr 5.0 only supports creating and removing SolrCloud collections through the Collections API, unlike previous versions. While not using the collections API may still work in 5.0, it is unsupported, not recommended, and the behavior will change in a 5.x release.

SolrJ changes

Many SolrJ methods that were marked deprecated in Solr 4.10 have been removed. Please consult the Solr 4.10 javadocs for the SolrJ package for information regarding the new supported methods.

In addition, the SolrServer family of classes are now deprecated, and developers are encouraged to instead use the SolrClient family of classes.

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