SPARQLify is a scalable SPARQL-SQL rewriter whose development began in April 2011 in the course of the LinkedGeoData project.

Features

SML support

Support of the 'Sparqlification Mapping Language' (SML), an intuitive language for expressing RDB-RDF mappings with only very little syntactic noise.

R2RML support

R2RML will be supported soon

Scalability

Sparqlify does not evaluate expressions in memory. All SPARQL filters end up in the corresponding SQL statement, giving the underlying RDBMS has maximum control over query planning.

Rewriting engine

A powerful rewriting engine that analyzes filter expressions in order to eleminate self joins and joins with unsatisfiable conditions.

Spatial support

Initial support for spatial datatypes and predicates.

SPARQL support

A subset of the SPARQL 1.0 query language plus sub queries are supported.

PostgreSQL/Postgis/H2 support

Tested with PostgreSQL/Postgis and H2. Support for further databases is planned.

CSV support

CSV support

CLI Tools

SPARQLify delivers sparqlify for RDB in postgres as well as sparqlify-csv for csv/excel files

Webadmin

SPARQLify delivers web admin functionality for servers

SPARQLify supports the following SPARQL language features:

  • Join, LeftJoin (i.e. Optional), Union, Sub queries
  • Filter predicates: comparison: (<=, <, =, >, >=) logical: (!, &&; ||) arithmetic: (+, -) spatial: st_intersects, geomFromText; other: regex, lang, langMatches
  • Aggregate functions: Count(*)
  • Order By is pushed into the SQL