As a matter of interest, would it be possible to develop RDF stores that optimize the layout of the data by analyzing the queries to the database? A bit like a Java Just In Time compiler analyses the usage of the classes in order to decide how to optimize the compilation.
Henry On 24 Sep 2008, at 20:30, Paul Gearon wrote:
A related point is that processing RDF to create an object means you have to move around a lot in the graph. This could mean a lot of seeking on disk, while an RDBMS will usually find the entire object in one place on the disk. And seeks kill performance. This leads to the operations used to build objects from an RDF store. A single object often requires the traversal of several statements, where the object of one statement becomes the subject of the next. Since the tables are typically represented as Subject/Predicate/Object, this means that the main table will be "joined" against itself. Even RDBMSs are notorious for not doing this efficiently.
