|Stable release||2.2.0 / March 25, 2015|
|License||Dual-licensed: GPLv3 and AGPLv3 / commercial|
Neo4j is an open-source graph database, implemented in Java. The developers describe Neo4j as "embedded, disk-based, fully transactional Java persistence engine that stores data structured in graphs rather than in tables". Neo4j is the most popular graph database.
Neo4j version 1.0 was released in February, 2010. The community edition of the database is licensed under the free GNU General Public License (GPL) v3. The additional modules, such as online backup and high availability, are licensed under the free Affero General Public License (AGPL) v3. The database, with the additional modules, is also available under a commercial license, in a dual license model.
Neo4j version 2.0 was released in December, 2013.
Neo4j was developed by Neo Technology, Inc., based in the San Francisco Bay Area, US and Malmö, Sweden. Neo Technology board of directors consists of Rod Johnson (founder of the Spring Framework), Chris Barchak (Partner at Conor Venture Partners), Magnus Christerson (Vice President of Intentional Software Corp), Nikolaj Nyholm (Partner at Sunstone Capital), Guarav Tuli (Principal at Fidelity Growth Partners) and Johan Svensson (CTO of Neo Technology).
Licensing and Editions
Neo4j comes in 2 editions: Community and enterprise. It is dual-licensed: GPLv3 and AGPLv3 / commercial. The community edition is free but is limited to running on 1 node only due to the lack of clustering and is without hot backups. The enterprise edition (which requires buying a license unless the application built on top of it is open-sourced) unlocks these limitations allowing for clustering, hot backups and monitoring.
In Neo4j, everything is stored in form of either an edge, a node or an attribute. Each node and edge can have any number of attributes. Both the nodes and edges can be labelled. Labeling is useful, because you can narrow down your searching area using the labels. As of version 2.0, indexing was added to Cypher with the introduction of schemas. Previously, indexes were supported separately from Cypher.
- Apache Giraph
- Structured storage
- Gremlin (programming language)
- Cypher Query Language
- Graph Database
- Todd Hoff (June 13, 2009). "Neo4j - a Graph Database that Kicks Buttox". High Scalability. Possibility Outpost. Retrieved February 17, 2010.
- Gavin Terrill (June 5, 2008). "Neo4j - an Embedded, Network Database". InfoQ. C4Media Inc. Retrieved February 17, 2010.
- "DB-Engines Ranking of Graph DBMS". DB-Engines. January 11, 2013. Retrieved January 11, 2013.
- "The top 10 ways to get to know Neo4j". Neo4j Blog. February 16, 2010. Retrieved February 17, 2010.
- Emil Eifrem (April 13, 2011). "Graph Databases, Licensing and MySQL". Retrieved April 29, 2011.
- "Neo4j 2.0 GA - Graphs for Everyone". Neo4j Blog. December 11, 2013. Retrieved January 10, 2014.
- Neo Technology. "Staff - Neo4Jj Graph Database". Retrieved February 18, 2015.
- "The Neo4j Editions".
- "The Neo4j Manual v2.1.5".
- "The Neo4j Manual v1.8.3".
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