Solr Upgrade Notes

Solr now uses Log4j v2.11. The Log4j configuration is now in log4j2.xml rather than log4j.properties files. This is a server side change only and clients using SolrJ won’t need any changes. Clients can still use any logging implementation which is compatible with SLF4J. We now let Log4j handle rotation of solr logs at startup, and bin/solr start scripts will no longer attempt this nor move existing console or garbage collection logs into logs/archived either. See Configuring Logging for more details about Solr logging.

Configuring slowQueryThresholdMillis now logs slow requests to a separate file named solr_slow_requests.log. Previously they would get logged in the solr.log file.

In the master-slave model of scaling Solr, a slave no longer commits an empty index when a completely new index is detected on master during replication. To return to the previous behavior pass false to skipCommitOnMasterVersionZero in the slave section of replication handler configuration, or pass it to the fetchindex command.

Collections created without specifying a configset name have used a copy of the _default configset since Solr 7.0. Before 7.3, the copied configset was named the same as the collection name, but from 7.3 onwards it will be named with a new ".AUTOCREATED" suffix. This is to prevent overwriting custom configset names.

The rq parameter used with Learning to Rank rerank query parsing no longer considers the defType parameter. See Running a Rerank Query for more information about this parameter.

The default value of autoReplicaFailoverWaitAfterExpiration, used with the AutoAddReplicas feature, has increased to 120 seconds from the previous default of 30 seconds. This affects how soon Solr adds new replicas to replace the replicas on nodes which have either crashed or shutdown.

The default Solr log file size and number of backups have been raised to 32MB and 10 respectively. See the section Configuring Logging for more information about how to configure logging.

The old Leader-In-Recovery implementation (implemented in Solr 4.9) is now deprecated and replaced. Solr will support rolling upgrades from old 7.x versions of Solr to future 7.x releases until the last release of the 7.x major version.

Replicas which are not up-to-date are no longer allowed to become leader. Use the FORCELEADER command of the Collections API to allow these replicas become leader.

The behaviour of the autoscaling system will now pause all triggers from execution between the start of actions and the end of a cool down period. The triggers will resume after the cool down period expires. Previously, the cool down period was a fixed period started after actions for a trigger event completed and during this time all triggers continued to run but any events were rejected and tried later.

The throttling mechanism used to limit the rate of autoscaling events processed has been removed. This deprecates the actionThrottlePeriodSeconds setting in the set-properties Autoscaling API which is now non-operational. Use the triggerCooldownPeriodSeconds parameter instead to pause event processing.

If you are using the spatial JTS library with Solr, you must upgrade to 1.15.0. This new version of JTS is now dual-licensed to include a BSD style license. See the section on Spatial Search for more information.

The top-level <highlighting> element in solrconfig.xml is now officially deprecated in favour of the equivalent <searchComponent> syntax. This element has been out of use in default Solr installations for several releases already.

Starting a query string with local parameters {!myparser …​} is used to switch from one query parser to another, and is intended for use by Solr system developers, not end users doing searches. To reduce negative side-effects of unintended hack-ability, Solr now limits the cases when local parameters will be parsed to only contexts in which the default parser is "lucene" or "func".

The eDisMax parser by default no longer allows subqueries that specify a Solr parser using either local parameters, or the older _query_ magic field trick.

The feature to automatically add replicas if a replica goes down, previously available only when storing indexes in HDFS, has been ported to the autoscaling framework. Due to this, autoAddReplicas is now available to all users even if their indexes are on local disks.

Shard and cluster metric reporter configuration now require a class attribute.

All Stream Evaluators in solrj.io.eval have been refactored to have a simpler and more robust structure. This simplifies and condenses the code required to implement a new Evaluator and makes it much easier for evaluators to handle differing data types (primitives, objects, arrays, lists, and so forth).

In the ReplicationHandler, the master.commitReserveDuration sub-element is deprecated. Instead please configure a direct commitReserveDuration element for use in all modes (master, slave, cloud).

The RunExecutableListener was removed for security reasons. If you want to listen to events caused by updates, commits, or optimize, write your own listener as native Java class as part of a Solr plugin.

In the XML query parser (defType=xmlparser or {!xmlparser …​ }) the resolving of external entities is now disallowed by default.