SPARQL

“SPARQL is a recursive acronym and stands for SPARQL Protocol and RDF Query Language). It is an RDF query language, that is, a semantic query language for databases, able to retrieve and manipulate data stored in Resource Description Framework (RDF) format.”

~ Wikipedia on SPARQL

“A NoSQL (originally referring to "non SQL" or "non relational") database provides a mechanism for storage and retrieval of data which is modeled in means other than the tabular relations used in relational databases.”

~ Wikipedia on NoSQL

• See w:List of SPARQL implementations for all w:triplestores that provide SPARQL querying endpoint
• See w:List of subject-predicate-object databases for purpose built triplestores.

Copyleft or free-of-charge implementations of SPARQL endpoint ability producing software alternatives

• w:Virtuoso Universal Server - http://virtuoso.openlinksw.com/download/

Tools

• http://d2rq.org/ - Enables writing queries in SPARQL that actually access traditional relational database and receiving results and RDF graphs. Could be very useful as glue code between MediaWiki's data in the MariaDB and the public and private SPARQL databases