We have received many requests for an embeddable-scale Virtuoso. In response to this, we have added a Lite mode, where the initial size of a server process is a tiny fraction of what the initial size would be with default settings. With 2MB of disk cache buffers (ini file setting, NumberOfBuffers = 256), the process size stays under 30MB on 32-bit Linux.

The value of this is that one can now have RDF and full text indexing on the desktop without running a Java VM or any other memory-intensive software. And of course, all of SQL (transactions, stored procedures, etc.) is in the same embeddably-sized container.

The Lite executable is a full Virtuoso executable; the Lite mode is controlled by a switch in the configuration file. The executable size is about 10MB for 32-bit Linux. A database created in the Lite mode will be converted into a fully-featured database (tables and indexes are added, among other things) if the server is started with the Lite setting "off"; functionality can be reverted to Lite mode, though it will now consume somewhat more memory, etc.

Lite mode offers full SQL and SPARQL/SPARUL (via SPASQL), but disables all HTTP-based services (WebDAV, application hosting, etc.). Clients can still use all typical database access mechanisms (i.e., ODBC, JDBC, OLE-DB, ADO.NET, and XMLA) to connect, including the Jena and Sesame frameworks for RDF. ODBC now offers full support of RDF data types for C-based clients. A Redland-compatible API also exists, for use with Redland v1.0.8 and later.

Especially for embedded use, we now allow restricting the listener to be a Unix socket, which allows client connections only from the localhost.

Shipping an embedded Virtuoso is easy. It just takes one executable and one configuration file. Performance is generally comparable to "normal" mode, except that Lite will be somewhat less scalable on multicore systems.

The Lite mode will be included in the next Virtuoso 5 Open Source release.