Triplestore

A triplestore is a purpose-built database for the storage and retrieval of triples, a triple being a data entity composed of subject-predicate-object, like "Bob is 35" or "Bob knows Fred".

Much like a relational database, one stores information in a triplestore and retrieves it via a query language. Unlike a relational database, a triplestore is optimized for the storage and retrieval of triples. In addition to queries, triples can usually be imported/exported using Resource Description Framework (RDF) and other formats.

Some triplestores can store billions of triples.

Implementation

Some triplestores have been built as database engines from scratch, while others have been built on top of existing commercial relational database engines (i.e. SQL-based). Like the early development of online analytical processing (OLAP) databases, this intermediate approach allowed large and powerful database engines to be constructed for little programming effort in the initial phases of triplestore development. Long-term though it seems likely that native triplestores will have the advantage for performance. A difficulty with implementing triplestores over SQL is that although triples may thus be stored, implementing efficient querying of a graph-based RDF model (i.e. mapping from SPARQL) onto SQL queries is difficult.

List of implementations

Name	Developed in language	Homepage	Licence
3store	C	www.aktors.org/technologies/3store, sourceforge.net/projects/threestore/	GPL
4store	C	www.4store.org	GPL v3
5store	C	4store.org/trac/wiki/5store
AllegroGraph	Common Lisp	www.franz.com/agraph/allegrograph
ARC	PHP	arc.semsol.org	W3C Software License or GPL
Bigdata	Java	www.bigdata.com	GPL v2 or Commercial or Research
BigOWLIM	Java	www.ontotext.com/owlim
BrightstarDB	C#	brightstardb.com
Dydra	Common Lisp, C	www.dydra.com
IBM DB2	Java, SQL	pic.dhe.ibm.com/infocenter/db2luw/v10r1/topic/com.ibm.swg.im.dbclient.rdf.doc/doc/c0059661.html
Apache Jena	Java	jena.apache.org	Apache 2
Mulgara	Java	www.mulgara.org
OntoBroker	Java	www.semafora-systems.com/en/products/ontobroker/
OpenAnzo	Java	www.openanzo.org
OpenLink Virtuoso	C	virtuoso.openlinksw.com	GPL v2 or Commercial
Oracle	Java, PL/SQL, SQL	www.oracle.com/technetwork/database-options/spatialandgraph/overview/rdfsemantic-graph-1902016.html
OWLIM	Java	www.ontotext.com/owlim
Meronymy SPARQL Database Server	C++	www.meronymy.com
Parliament	Java, C++	parliament.semwebcentral.org	BSD license
Pointrel System	Java, Python	sourceforge.net/projects/pointrel	LGPLv3
Profium Sense	Java	www.profium.com/technologies/profium-sense
RAP	PHP	www4.wiwiss.fu-berlin.de/bizer/rdfapi
RDF::Core	Perl	search.cpan.org/dist/RDF-Core
RDF::Trine	Perl	www.perlrdf.org	Same as Perl
RDF-3X	C++	www.mpi-inf.mpg.de/~neumann/rdf3x	CC-BY-NC-SA 3.0
RDFBroker	Java	rdfbroker.opendfki.de
Redland	C	librdf.org	Apache or LGPL or GPL
RedStore	C	www.aelius.com/njh/redstore
Saffron Memory Base	Java	www.saffrontech.con
Semantics Platform	C#	www.intellidimension.com
SemWeb-DotNet	C#	razor.occams.info/code/semweb
Sesame	Java	www.openrdf.org	BSD-style license
Soprano	C++	soprano.sourceforge.net	LGPLv2
Stardog	Java	stardog.com
StrixDB	C++, Lua	www.strixdb.com
YARS	Java	sw.deri.org/2004/06/yars
Smart-M3	Python, Java, C, C#	sourceforge.net/projects/smart-m3	BSD License

Technical overview

The following table is an overview of available triplestores, their technical implementation, support for the SPARQL World Wide Web Consortium (W3C) recommendations, and available application programming interfaces (API).

Solution Name	Native storage	Native SPARQL support	Native SPARQL/Update support	Native SPARQL Protocol Endpoint	Native APIs
4store	Triplestore	√	√	√	Command line only
AllegroGraph	Graph	√	√	√	For most modern programming languages
ARC2	3rd party	√	√	√	PHP
ARQ	3rd party	√	√		Java
BigData	Triplestore	√	√	√	Java
BrightstarDB	Graph data model in Heap file	√			.NET Framework or Web Service
Corese	3rd party	√			Java
D2R Server	3rd party	√	√	√	Java
Dydra	Graph database in the cloud SaaS	√	√	√	REST API
Hercules	Stored in web browser	√			JavaScript
IBM DB2	Object-relational				Java
Intellidimension Semantics Platform 2.0	3rd party	√			.NET Framework
Jena	Tuple store	√	√	√	Java
KAON2	3rd party	√			Java
Meronymy SPARQL Database Server	Triplestore / Quadstore	√	√	√	For most modern programming languages
Mulgara	3rd party	√			Java or REST API
OntoBroker	Triplestore	√	√	√	Java
Ontotext OWLIM	3rd party	√	√	√	Java
Open Anzo	3rd party	√		√	Java, JavaScript, .NET Framework
OpenLink Virtuoso	Hybrid (Relational Tables and Relational Property Graphs)	√	√	√	ODBC, JDBC, ADO.NET, OLE DB, XMLA, HTTP, etc., serving most modern programming languages including C, PHP, Perl, Python, Ruby, Java, JavaScript, .NET Framework, etc.
Oracle DB Enterprise Ed.	Object-relational				For most modern programming languages
Parliament	3rd party	√	√	√	Java or C++
Pellet	3rd party	√			Java
Pointrel	Triplestore				Python
Profium Sense	In-memory triplestore	√		√	Java
RAP	In-memory triplestore or heap file	√			PHP
RDF API for PHP	3rd party	√			PHP
RDF::Query	3rd party	√	√	√	Perl
RDF-3X	Triplestore	√			Command line only
RDFBroker	3rd party				Java
Redland, Redstore	3rd party	√	√	√	C
SemWeb.NET	3rd party	√		√	.NET Framework
Sesame 2	3rd party	√			Java
Soprano	3rd party				C++
SPARQL Engine	3rd party	√			Java
Stardog	3rd party	√		√	Java, Groovy
StrixDB	Triplestore	√	√	√	Lua
Twinql	3rd party	√			Lisp
YARS	3rd party				HTTP, JDBC

See also

• Freebase uses a triplestore called graphd
• Named graph a.k.a. "quad store"

External links

• A list of large triplestores
• Lehigh University Benchmark (LUBM)
• How RDF Databases Differ from Other NoSQL Solutions
• W3C SPARQL Working Group, was RDF Data Access Working Group
• SPARQL Query language
• SPARQL Protocol
• SPARQL 1.1 Update W3C Recommendation 21 March 2013