Datalog notes

####Why Datalog over SPARQL?

• Datalog allows general recursion; SPARQL only allows structural recursion in recent version
• Lots of research on optimization in the 80's
• Some commerical success (http://www.logicblox.com/)

relational algebra -> nested loops

• select
• project
• join

use cases

• applications that generate queries
• alerts
• people who write queries

example systems

• client database
  • pull-down menu-ish thing
  • originally sgi uv, porting to xmt2
• lexis-nexis

Other semantic databases

• http://en.wikipedia.org/wiki/Virtuoso_Universal_Server