While it's early days yet, column databases storing something like RDF may get faster than row-oriented SQL databases. I posted about column databases storing RDF previously.
"Vertica beats all row stores on the planet -- typically by a factor of 50," he wrote. "The only engines that come closer are other column stores, which Vertica typically beats by around a factor of 10."
And from the cited blog:
In addition, it provides built-in features appropriate to the needs of 2007 customers. These include:
o Linear scalability over a shared-nothing hardware grid
o Automatic high availability
o Automatic use of materialized views
o "No knobs" -- minimum DBA requirements
Seeing as though I've just been looking into this here are a few references:
- The End of an Architectural Era (It’s Time for a Complete Rewrite) One of the links from my previous post written by Michael Stonebraker and others. It provides a deeper explanation of column databases than in the above articles.
- Decomposition Storage Model the paper that started it all (from 1985). Section 2.5 is especially relevant as it mentions how to store directed graphs and parent-child relationships.
- Database Architecture Optimized for the New Bottleneck: Memory Access
- Monet: A Next-generation DBMS Kernel for Query-intensive Applications
Update 2: While I'm normally pretty skeptical about most things, column databases have had their own fair share of problems in the past.