Graph database

In computing, a graph database is a database that uses graph structures for semantic queries with nodes, edges and properties to represent and store data. A graph database is any storage system that provides index-free adjacency.[1] This means that every element contains a direct pointer to its adjacent elements and no index lookups are necessary. General graph databases that can store any graph are distinct from specialized graph databases such as triplestores and network databases.

Structure

Graph databases are based on graph theory. Graph databases employ nodes, properties, and edges.

Nodes represent entities such as people, businesses, accounts, or any other item you might want to keep track of.

Properties are pertinent information that relate to nodes. For instance, if "Wikipedia" were one of the nodes, one might have it tied to properties such as "website", "reference material", or "word that starts with the letter 'w'", depending on which aspects of "Wikipedia" are pertinent to the particular database.

Edges are the lines that connect nodes to nodes or nodes to properties and they represent the relationship between the two. Most of the important information is really stored in the edges. Meaningful patterns emerge when one examines the connections and interconnections of nodes, properties, and edges.

Properties

Compared with relational databases, graph databases are often faster for associative data sets and map more directly to the structure of object-oriented applications. They can scale more naturally to large data sets as they do not typically require expensive join operations. As they depend less on a rigid schema, they are more suitable to manage ad hoc and changing data with evolving schemas. Conversely, relational databases are typically faster at performing the same operation on large numbers of data elements.

Graph databases are a powerful tool for graph-like queries, for example computing the shortest path between two nodes in the graph. Other graph-like queries can be performed over a graph database in a natural way (for example graph's diameter computations or community detection).

Graph database projects

The following is a list of several well-known graph database projects:

Name Version License Language Description
AllegroGraph 4.14.1 (September 2014) Proprietary, Clients - Eclipse Public License v1 C#, C, Common Lisp, Java, Python A RDF and graph database.
ArangoDB 2.4.4 (February 2015) Apache 2 C, C++ & Javascript A distributed multi-model document store and graph database. Highly scalable supporting ACID and full transaction support. Including a built-in graph explorer.
Blazegraph 1.5.1 (March 2015) GPLv2, evaluation license, or commercial license. Java A RDF/graph database capable of clustered deployment. Blazegraph supports high availability (HA) mode, embedded mode, single server mode. As of version 1.3.1, it supports the Blueprints API and Reification Done Right (RDR). Prior to version 1.5.0, Blazegraph was known as Bigdata.
Bitsy 1.5.0 AGPL, Enterprise license (unlimited use, annual/perpetual) Java A small, embeddable, durable in-memory graph database
BrightstarDB MIT License [2] C# An embeddable NoSQL database for the .NET platform with code-first data model generation.
Cayley 0.4.0 (August 2014) Apache 2 Go An open-source graph inspired by the graph database behind Freebase and Google's Knowledge Graph.
DEX/Sparksee[3] 5.1.0 (2014) evaluation, research or development use (free) / commercial use C++ A high-performance and scalable graph database management system from Sparsity Technologies, a technology transition company from DAMA-UPC. Its main characteristics is its query performance for the retrieval & exploration of large networks. Sparksee 5 mobile is the first graph database for mobile devices.
Filament BSD Java A graph persistence framework and associated toolkits based on a navigational query style.
GraphBase 1.0.03a Proprietary Java A customizable, distributed, small-footprint graph store with a rich tool set from FactNexus.
Graphd Proprietary The proprietary back-end of Freebase.
Grapholytic 0.1 Proprietary A distributed GraphDB from MIOsoft.
Horton Proprietary C# A graph database from Microsoft Research Extreme Computing Group (XCG) based on the cloud programming infrastructure Orleans.
HyperGraphDB 1.2 (2012) LGPL Java A graph database supporting generalized hypergraphs where edges can point to other edges.
IBM System G Native Store v1.0 (July 2014) Proprietary C, C++, Java A high performance graph store using natively implemented graph data structures and primitives for achieving superior efficiency. IBM System G Native Store can handle various simple graphs, property graphs, and RDF graphs, in terms of storage, analytics, and visualization. Native Store is accessible from most programming languages by providing APIs in C++, Java (Tinkerpop/Blueprints), and Python. Its gShell graph command collection and the Native Store REST APIs provide language-free interfaces.
InfiniteGraph 3.0 (January 2013) Proprietary Java A distributed and cloud-enabled commercial product with flexible licensing.
InfoGrid 2.9.5 (2011) AGPLv3, free for small entities[4] Java A graph database with web front end and configurable storage engines (MySQL, PostgreSQL, Files, Hadoop).
jCoreDB Graph An extensible database engine with a graph database subproject.
MapGraph v3 (2014) Apache 2 CUDA MapGraph is Massively Parallel Graph processing on GPUs. The MapGraph API makes it easy to develop high performance graph analytics on GPUs. The API is based on the Gather-Apply-Scatter (GAS) model as used in GraphLab. MapGraph is up to two orders of magnitude faster than parallel CPU implementations on up 24 CPU cores and has performance comparable to a state-of-the-art manually optimized GPU implementation. New algorithms can be implemented in a few hours that fully exploit the data-level parallelism of the GPU and offer throughput of up to 3.3 billion traversed edges per second on a single GPU.[5] and up to 30 billion traversed edges per second on a cluster with 64 GPUs [6]
Neo4j 2.2.0 (March 2015) GPLv3 Community Edition. Commercial & AGPLv3 options for Enterprise and Advanced editions Java A highly scalable open source graph database that supports ACID, has high-availability clustering for enterprise deployments, and comes with a web-based administration tool that includes full transaction support and visual node-link graph explorer. Neo4j is accessible from most programming languages using its built-in REST web API interface. Neo4j is the most popular graph database in use today.[7]
OpenCog AGPL C++, Scheme, Python Includes a satisfiability modulo theories solver and a unified rule engine for performing both crisp (boolean) logic and probabalistic reasoning. Backed onto Postgres.
Ontotext GraphDB 6.1 GraphDB Lite is free
GraphDB Standard and GraphDB Enterprise are commercially licensed
Java A graph database engine, based entirely on Semantic Web standards from W3C: RDF, RDFS, OWL, SPARQL. GraphDB Lite is an "in memory" engine. GraphDB Standard is robust standalone database engine. GraphDB Enterprise is a clustered version which offers horizontal scalability and failover support and other enterprise features.
Orly (March 2014) Apache 2 C++ A highly scalable open source graph database. Orly is accessible from most programming languages using its built-in REST web API interface.
OpenLink Virtuoso 7.1 (March 2014) GPLv2 for Open Source Edition. Proprietary for Enterprise Edition. C, C++ A hybrid database server handling RDF and other graph data, RDB/SQL data, XML data, filesystem documents/objects, and free text. May be deployed as a local embedded instance (as used in the Nepomuk Semantic Desktop), a single-instance network server, or a shared-nothing elastic-cluster multiple-instance networked server.[8]
Oracle Spatial and Graph 11.2 (2012) Proprietary Java, PL/SQL 1) RDF Semantic Graph: comprehensive W3C RDF graph management in Oracle Database with native reasoning and triple-level label security. 2) Network Data Model property graph: for physical/logical networks with persistent storage and a Java API for in-memory graph analytics.
Oracle NoSQL Database 2.0.39 (2013) Proprietary Java RDF Graph for Oracle NoSQL Database is a feature of Enterprise Edition providing W3C RDF graph capabilities in NoSQL Database.
OrientDB 2.0.1 (January 2015) Community Edition Apache 2, Enterprise Edition is Commercial Java OrientDB is a 2nd Generation Distributed Graph Database with the flexibility of Documents in one product with an Open Source commercial friendly license (Apache 2 license). It has a multi-master replication and sharding. Supports schema-less, schema-full and schema-mixed modes. Has a strong security profiling system based on user and roles and supports SQL amongst the query languages. Thanks to the SQL layer, it's straightforward to use for those skilled in the relational database world.
OQGRAPH GPLv2 A graph computation engine for MySQL, MariaDB and Drizzle.
Profium Sense 6.0 Proprietary Java Profium Sense is a contextual content management platform with a built-in triple store. Profium's own reasoning engine supports OWL 2 RL and RDFS and is optimized to manage continuous information streams that require continuous inferencing on-the-fly. Profium architecture is based on an in-memory database with ACID transaction support and supports distributed high-availability deployment.
R2DF R2DF framework for ranked path queries over weighted RDF graphs.
ROIS Freeware Modula-2 A programmable knowledge server that supports inheritance and transitivity. Used in OpenGALEN as a Terminology Server.
sones GraphDB AGPLv3 C# A graph database and universal access layer (funded by Deutsche Telekom). Sones GraphDB is not longer in production. Sones declared bankruptcy in January 2012 and the GraphDB brand was acquired by Ontotext.
SPARQLCity v1.0.95 (October 2014) GPLv3 C, C++ & Javascript SPARQLCity produces SPARQLVerse: A standards and Hadoop based analytic graph engine for performing rich business analytics on structured and semi-structured data.
Sqrrl Enterprise v1.5.1 (August 2014) Proprietary Java Distributed, real-time graph database featuring cell-level security and massive scalability.
Stardog v2.2 (July 2014) Proprietary Java Fast, scalable, pure Java semantic graph database.
Teradata Aster v6 (2013) Proprietary Java, SQL, Python, C++, R A high performance, multi-purpose, highly scalable and extensible MPP database incorporating patented engines supporting native SQL, MapReduce and Graph data storage and manipulation. An extensive set of analytical function libraries and data visualization capabilities are also provided.
Titan 0.5.2 (2014) Apache 2 Java A distributed, real-time, scalable transactional graph database developed by Aurelius.
Trinity C#, C, X64 Assembly A distributed general purpose graph engine on a memory cloud.
TripleBit C/C++ A centralized RDF store.
VelocityGraph Open source with proprietary back-end C# High performance, scalable & flexible graph database build with VelocityDB object database.
VertexDB Revised BSD C A graph database server that supports automatic garbage collection.
Weaver 0.1 (December 2014) BSD licenses C, Python A fast, scalable, ACID transactional graph database with replication and migration.
WhiteDB 0.7.0 (October 2013) GPLv3 and a free commercial licence C A graph/N-tuples shared memory database library.
OhmDB 1.0.0 (August 2014) Apache 2 Java RDBMS + NoSQL Database for Java.

Graph database features

The following table compares the features of the above graph databases.

Name Graph Model API Query Methods Visualizer Consistency Backend Scalability
AllegroGraph RDF Java, Java:Sesame, JavaJena, Python, Ruby, Perl, C#, Clojure, Lisp, Scala, REST SPARQL 1.1, Prolog, JIG, JavaScript Gruff - View Graphs, Visual Query Builder for SPARQL and Prolog ACID Native Graph Storage1 Trillion RDF triples
ArangoDB Property Graph JavaScript, Blueprints, REST Graph Traversals via JavaScript, Gremlin Built-in graph explorer MVCC/ACID native C/C++ Replication and Sharding
Blazegraph RDF Java, Sesame, Blueprints, Gremlin, SPARQL, REST SPARQL, Gremlin Blazegraph Workbench UI MVCC/ACID Native Java Embedded, Client/Server, High Availability (HA)
Bitsy Property Graph Blueprints Gremlin, Pixy ACID with optimistic concurrency control Human-readable JSON-encoded text files with checksums and markers for recovery
DEX/Sparksee[9] Labeled and directed attributed multigraph Java, C++, .NET, Python Native Java, C#, Python and C++ APIs, Blueprints, Gremlin Exporting functionality to visualization formats Consistency, durability and partial isolation and atomicity Native graph. light and independent data structures with a small memory footprint for storage Master/Slave replication
Filament
GraphBase Enterprise(1) GraphBase Agility(2) (1) mixed, (2) Framework-managed Simple Graph Java Bounds Language, embedded java GraphPad, BoundsPad, Navigator ACID, graph-based transactions proprietary native (1) shared nothing distributed, (2) simple replication, 100+ Billion arcs per server
Horton Attributed multigraph Horton Query Language (Regular Language Expression + SQL) C#, .Net Framework, Asynchronous communication protocols
HyperGraphDB Object-oriented multi-relational labeled hypergraph Custom,Java MVCC/STM
IBM System G Native Store Property Graph, RDF* C++, Java, Python Native Store gShell, Gremlin, SPARQL Built-in Visualizer ACID Native Graph Storage Both scale-up (using multithreading) and scale-out (using IBM PAMI)
InfiniteGraph Labeled and directed multi-property graph Java, Blueprints (Read Only) Java (with parallel, distributed queries), Gremlin (Read Only) Graph browser for developers. Plugins to allow use of external libraries. ACID. There is also a parallel, loosely synchronized batch loader. Objectivity/DB on standard filesystems Distributed & Sharded. Objectivity/DB was the first DBMS to store a Petabyte of objects.
InfoGrid Dynamically typed, object-oriented graph, multigraphs, semantic models
Neo4j Property Graph Java, Python, JPython, Ruby, JRuby, JavaScript (Node.js), PHP, .NET, Django, Clojure, Spring, Scala, or REST (any language) Cypher (native/preferred), Native Java APIs (special cases), Traverser API, REST, Blueprints, Gremlin Data Browser included. Supports a variety of 3rd party tools: Gephi, Linkurio.us, Cytoscape, Tom Sawyer, Keylines, etc. ACID Native graph storage with native graph processing engine Horizontal read scaling via master-slave clustering with cache sharding.
Ontotext GraphDB RDF TriplestoreJava: Sesame, Jena REST APIs: SPARQL 1.1 Protocol (end-point), SPARQL 1.1 Graph Store HTTP Protocol, Linked Data Platform, SPARQL results in JSON, JSON-LD and all RDF syntaxes SPARQL 1.1 (full support), Geo-spatial extension of SPARQL, FTS extensions: Lucene, SOLR, Elasticsearch queries, through GraphDB Connectors GraphDB Workbench: Explore, SPARQL queries, repository management, cluster management, RelFinder.) Persistent, Synchronous, Asynchronous Native Graph Storage Master/Slave Replication, High-Availability Clustering
OpenLink Virtuoso RDF graph: Triple & Quad (named graphs); expandable column store SPARQL, XMLA, ODBC, JDBC, ADO.NET, OLE DB, Jena, Sesame, Virtuoso PL/SQL, Java, Python, Perl, PHP, HTTP, etc. SPARQL 1.1; SPARQL web service endpoint; SQL; others Pivot Viewer (Silverlight or HTML5); OpenLink Data Explorer; SPARQL-compliant tools; Apache Jena-based tools; XML & JSON-based tools; SQL based tools ACID Internal column-store or row-store (depending on licensure), hybrid RDF/SQL/RDB engine Infinite via Commercial Edition's Cluster Module elastic cluster functionality; simple master-slave clustering of single-server instances also an option.
Oracle Spatial and Graph RDF graph: Triple & Quad (named graphs); Network Data Model property graph Java; Apache Jena; PL/SQL SPARQL 1.1; SPARQL web service end point; SQL SPARQL-compliant tools; Apache Jena-based tools; XML & JSON-based tools; SQL based tools ACID Efficient, compressed, partitioned graph storage; Native persisted in-database inferencing; SPARQL 1.1 & SQL integration; Triple-level label security; Semantic indexing of documents Parallel load, query, inference; Query controls; Scales from PC to Oracle Exadata; Supports Oracle Real Application Clusters and Oracle Database 8 exabytes
Oracle NoSQL Database RDF graph: Triple default graph, Triple & Quad named graphs Java (Apache Jena) SPARQL 1.1; SPARQL web service end point SPARQL-compliant tools; Apache Jena-based tools; XML & JSON-based tools ACID; Configurable consistency & durability policies Key/value store; W3C SPARQL 1.1 & Update; In-memory RDFS/OWL inferencing Parallel load/query; Query controls for: parallel execution, timeout, query optimization hints
OrientDB Property Graph Java, Python, JPython, Ruby, JRuby, JavaScript (Node.js), PHP, .NET, Clojure, Spring, Scala, or REST (any language) Own SQL-like Query Language, REST, Blueprints, Gremlin, SparQL (via Blueprints) Console and Studio Web tool supporting also graph editor ACID, MVCC Custom on disc or in memory Horizontal read and write scaling via multi-master replication + sharding.
OQGRAPH Property Graph SQL ACID MySQL, MariaDB
Sones GraphDB Property Graph REST API, Java, C# Own SQL-like Query Language, XML/JSON, Gremlin MVCC/ACID Microsoft Cloud Azure Services Platform
Sqrrl Enterprise Property Graph Thrift, Blueprint Own SQL-like query language and Java API Integrates with 3rd party tools Fully Consistent and ACID (transactions limited to a single graph node) Apache Accumulo Distributed cluster with tens of trillions of edges
Stardog RDF Java, Sesame, Jena, SNARL, HTTP/REST, Python, Ruby, Node.js, C#, Clojure, Spring SPARQL 1.1 Stardog Web, Pelorus ACID Native Graph Storage 50 billion RDF triples on $10,000 server
Titan Property Graph Java, Blueprints, REST, RexPro binary protocol, Python, Clojure (any language) Gremlin, SPARQL Integrates with 3rd party tools ACID or Eventually Consistent Apache Cassandra, Apache HBase, MapR M7 Tables, Berkeley DB, Persistit, Hazelcast Distributed cluster (120 billion+ edges) or single server.
Trinity Cell Based Graph Model C# Trinity Query Language Cell level Atomicity Native graph store and processing engine billion node in-memory graph
TripleBit Labeled direct graph C, C++ SPARQL ACID or Eventually Consistent] Native graph store and processing engine billion triples
VertexDB AJAX API JSON
Weaver Property Graph C, Python Node programs ACID HyperDex Automatic replication and migration

Distributed Graph Processing

GPGPU Graph Processing

APIs and Graph Query/Programming Languages

See also

References