solr/solr-ref-guide/src/major-changes-from-solr-5-to-solr-6.adoc - lucene-solr - Git at Google

 = Major Changes from Solr 5 to Solr 6
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 // "License"); you may not use this file except in compliance
 // with the License.  You may obtain a copy of the License at
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 // KIND, either express or implied.  See the License for the
 // specific language governing permissions and limitations
 // under the License.

 There are some major changes in Solr 6 to consider before starting to migrate your configurations and indexes.

 There are many hundreds of changes, so a thorough review of the <<solr-upgrade-notes.adoc#,Solr Upgrade Notes>> section as well as the {solr-javadocs}/changes/Changes.html[CHANGES.txt] file in your Solr instance will help you plan your migration to Solr 6. This section attempts to highlight some of the major changes you should be aware of.

 == Highlights of New Features in Solr 6

 Some of the major improvements in Solr 6 include:

 [[major-5-6-streaming]]
 === Streaming Expressions

 Introduced in Solr 5, <<streaming-expressions.adoc#,Streaming Expressions>> allow querying Solr and getting results as a stream of data, sorted and aggregated as requested.

 Several new expression types have been added in Solr 6:

 * Parallel expressions using a MapReduce-like shuffling for faster throughput of high-cardinality fields.
 * Daemon expressions to support continuous push or pull streaming.
 * Advanced parallel relational algebra like distributed joins, intersections, unions and complements.
 * Publish/Subscribe messaging.
 * JDBC connections to pull data from other systems and join with documents in the Solr index.

 [[major-5-6-parallel-sql]]
 === Parallel SQL Interface

 Built on streaming expressions, new in Solr 6 is a <<parallel-sql-interface.adoc#,Parallel SQL interface>> to be able to send SQL queries to Solr. SQL statements are compiled to streaming expressions on the fly, providing the full range of aggregations available to streaming expression requests. A JDBC driver is included, which allows using SQL clients and database visualization tools to query your Solr index and import data to other systems.

 === Cross Data Center Replication

 Replication across data centers is now possible with <<cross-data-center-replication-cdcr.adoc#,Cross Data Center Replication>>. Using an active-passive model, a SolrCloud cluster can be replicated to another data center, and monitored with a new API.

 === Graph QueryParser

 A new <<other-parsers.adoc#graph-query-parser,`graph` query parser>> makes it possible to to graph traversal queries of Directed (Cyclic) Graphs modelled using Solr documents.

 [[major-5-6-docvalues]]
 === DocValues

 Most non-text field types in the Solr sample configsets now default to using <<docvalues.adoc#,DocValues>>.

 == Java 8 Required

 The minimum supported version of Java for Solr 6 (and the <<using-solrj.adoc#,SolrJ client libraries>>) is now Java 8.

 == Index Format Changes

 Solr 6 has no support for reading Lucene/Solr 4.x and earlier indexes. Be sure to run the Lucene `IndexUpgrader` included with Solr 5.5 if you might still have old 4x formatted segments in your index. Alternatively: fully optimize your index with Solr 5.5 to make sure it consists only of one up-to-date index segment.

 == Managed Schema is now the Default

 Solr's default behavior when a `solrconfig.xml` does not explicitly define a `<schemaFactory/>` is now dependent on the `luceneMatchVersion` specified in that `solrconfig.xml`. When `luceneMatchVersion < 6.0`, `ClassicIndexSchemaFactory` will continue to be used for back compatibility, otherwise an instance of <<schema-factory-definition-in-solrconfig.adoc#,`ManagedIndexSchemaFactory`>> will be used.

 The most notable impacts of this change are:

 * Existing `solrconfig.xml` files that are modified to use `luceneMatchVersion >= 6.0`, but do _not_ have an explicitly configured `ClassicIndexSchemaFactory`, will have their `schema.xml` file automatically upgraded to a `managed-schema` file.
 * Schema modifications via the <<schema-api.adoc#,Schema API>> will now be enabled by default.

 Please review the <<schema-factory-definition-in-solrconfig.adoc#,Schema Factory Definition in SolrConfig>> section for more details.

 == Default Similarity Changes

 Solr's default behavior when a Schema does not explicitly define a global <<other-schema-elements.adoc#,`<similarity/>`>> is now dependent on the `luceneMatchVersion` specified in the `solrconfig.xml`. When `luceneMatchVersion < 6.0`, an instance of `ClassicSimilarityFactory` will be used, otherwise an instance of `SchemaSimilarityFactory` will be used. Most notably this change means that users can take advantage of per Field Type similarity declarations, without needing to also explicitly declare a global usage of `SchemaSimilarityFactory`.

 Regardless of whether it is explicitly declared, or used as an implicit global default, `SchemaSimilarityFactory` 's implicit behavior when a Field Types do not declare an explicit `<similarity />` has also been changed to depend on the `luceneMatchVersion`. When `luceneMatchVersion < 6.0`, an instance of `ClassicSimilarity` will be used, otherwise an instance of `BM25Similarity` will be used. A `defaultSimFromFieldType` init option may be specified on the `SchemaSimilarityFactory` declaration to change this behavior. Please review the `SchemaSimilarityFactory` javadocs for more details.

 == Replica & Shard Delete Command Changes

 DELETESHARD and DELETEREPLICA now default to deleting the instance directory, data directory, and index directory for any replica they delete. Please review the <<collections-api.adoc#,Collection API>> documentation for details on new request parameters to prevent this behavior if you wish to keep all data on disk when using these commands.

 == facet.date.* Parameters Removed

 The `facet.date` parameter (and associated `facet.date.*` parameters) that were deprecated in Solr 3.x have been removed completely. If you have not yet switched to using the equivalent <<faceting.adoc#,`facet.range`>> functionality you must do so now before upgrading.
	= Major Changes from Solr 5 to Solr 6
	// Licensed to the Apache Software Foundation (ASF) under one
	// or more contributor license agreements. See the NOTICE file
	// distributed with this work for additional information
	// regarding copyright ownership. The ASF licenses this file
	// to you under the Apache License, Version 2.0 (the
	// "License"); you may not use this file except in compliance
	// with the License. You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing,
	// software distributed under the License is distributed on an
	// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
	// KIND, either express or implied. See the License for the
	// specific language governing permissions and limitations
	// under the License.

	There are some major changes in Solr 6 to consider before starting to migrate your configurations and indexes.

	There are many hundreds of changes, so a thorough review of the <<solr-upgrade-notes.adoc#,Solr Upgrade Notes>> section as well as the {solr-javadocs}/changes/Changes.html[CHANGES.txt] file in your Solr instance will help you plan your migration to Solr 6. This section attempts to highlight some of the major changes you should be aware of.

	== Highlights of New Features in Solr 6

	Some of the major improvements in Solr 6 include:

	[[major-5-6-streaming]]
	=== Streaming Expressions

	Introduced in Solr 5, <<streaming-expressions.adoc#,Streaming Expressions>> allow querying Solr and getting results as a stream of data, sorted and aggregated as requested.

	Several new expression types have been added in Solr 6:

	* Parallel expressions using a MapReduce-like shuffling for faster throughput of high-cardinality fields.
	* Daemon expressions to support continuous push or pull streaming.
	* Advanced parallel relational algebra like distributed joins, intersections, unions and complements.
	* Publish/Subscribe messaging.
	* JDBC connections to pull data from other systems and join with documents in the Solr index.

	[[major-5-6-parallel-sql]]
	=== Parallel SQL Interface

	Built on streaming expressions, new in Solr 6 is a <<parallel-sql-interface.adoc#,Parallel SQL interface>> to be able to send SQL queries to Solr. SQL statements are compiled to streaming expressions on the fly, providing the full range of aggregations available to streaming expression requests. A JDBC driver is included, which allows using SQL clients and database visualization tools to query your Solr index and import data to other systems.

	=== Cross Data Center Replication

	Replication across data centers is now possible with <<cross-data-center-replication-cdcr.adoc#,Cross Data Center Replication>>. Using an active-passive model, a SolrCloud cluster can be replicated to another data center, and monitored with a new API.

	=== Graph QueryParser

	A new <<other-parsers.adoc#graph-query-parser,`graph` query parser>> makes it possible to to graph traversal queries of Directed (Cyclic) Graphs modelled using Solr documents.

	[[major-5-6-docvalues]]
	=== DocValues

	Most non-text field types in the Solr sample configsets now default to using <<docvalues.adoc#,DocValues>>.

	== Java 8 Required

	The minimum supported version of Java for Solr 6 (and the <<using-solrj.adoc#,SolrJ client libraries>>) is now Java 8.

	== Index Format Changes

	Solr 6 has no support for reading Lucene/Solr 4.x and earlier indexes. Be sure to run the Lucene `IndexUpgrader` included with Solr 5.5 if you might still have old 4x formatted segments in your index. Alternatively: fully optimize your index with Solr 5.5 to make sure it consists only of one up-to-date index segment.

	== Managed Schema is now the Default

	Solr's default behavior when a `solrconfig.xml` does not explicitly define a `<schemaFactory/>` is now dependent on the `luceneMatchVersion` specified in that `solrconfig.xml`. When `luceneMatchVersion < 6.0`, `ClassicIndexSchemaFactory` will continue to be used for back compatibility, otherwise an instance of <<schema-factory-definition-in-solrconfig.adoc#,`ManagedIndexSchemaFactory`>> will be used.

	The most notable impacts of this change are:

	* Existing `solrconfig.xml` files that are modified to use `luceneMatchVersion >= 6.0`, but do _not_ have an explicitly configured `ClassicIndexSchemaFactory`, will have their `schema.xml` file automatically upgraded to a `managed-schema` file.
	* Schema modifications via the <<schema-api.adoc#,Schema API>> will now be enabled by default.

	Please review the <<schema-factory-definition-in-solrconfig.adoc#,Schema Factory Definition in SolrConfig>> section for more details.

	== Default Similarity Changes

	Solr's default behavior when a Schema does not explicitly define a global <<other-schema-elements.adoc#,`<similarity/>`>> is now dependent on the `luceneMatchVersion` specified in the `solrconfig.xml`. When `luceneMatchVersion < 6.0`, an instance of `ClassicSimilarityFactory` will be used, otherwise an instance of `SchemaSimilarityFactory` will be used. Most notably this change means that users can take advantage of per Field Type similarity declarations, without needing to also explicitly declare a global usage of `SchemaSimilarityFactory`.

	Regardless of whether it is explicitly declared, or used as an implicit global default, `SchemaSimilarityFactory` 's implicit behavior when a Field Types do not declare an explicit `<similarity />` has also been changed to depend on the `luceneMatchVersion`. When `luceneMatchVersion < 6.0`, an instance of `ClassicSimilarity` will be used, otherwise an instance of `BM25Similarity` will be used. A `defaultSimFromFieldType` init option may be specified on the `SchemaSimilarityFactory` declaration to change this behavior. Please review the `SchemaSimilarityFactory` javadocs for more details.

	== Replica & Shard Delete Command Changes

	DELETESHARD and DELETEREPLICA now default to deleting the instance directory, data directory, and index directory for any replica they delete. Please review the <<collections-api.adoc#,Collection API>> documentation for details on new request parameters to prevent this behavior if you wish to keep all data on disk when using these commands.

	== facet.date.* Parameters Removed

	The `facet.date` parameter (and associated `facet.date.*` parameters) that were deprecated in Solr 3.x have been removed completely. If you have not yet switched to using the equivalent <<faceting.adoc#,`facet.range`>> functionality you must do so now before upgrading.