Christian Becker has delivered the final cut
of an initial iteration of his DBpedia based RDF Data Stores benchmark. This particular
exercise brought some very interesting things to our attention re.
Virtuoso's default mode of operation:
-
Virtuoso is a Quad Store in a Triple Store
world -- it supports RDF data
set storage partitioning via Named Graphs and it requires the use of the
SPARQL FROM clause to scope query patterns
to appropriate data
sets. Otherwise, it looks across all hosted data sets for matching
patterns
- We should be able to use our server side configuration settings
to make the Quad Store behave like a Triple Store (meaning we set
the list of applicable named graphs as part of the session
configuration)
- Provide hints to users about missing POGS, PSOG, and SOPG
bitmap indexes when SPARQL query patterns
received by the server are deemed suboptimal (we do know the
execution costs of each query)
How Do I create the missing Bitmap Indexes?
Go to the HTML based Virtuoso Conductor, iSQL command
line interface, or an ODBC / JDBC /
ADO.NET / OLE
DB client and execute:
CREATE BITMAP index RDF_QUAD_POGS on DB.DBA.RDF_QUAD (P,O,G,S);
CREATE BITMAP index RDF_QUAD_PSOG on DB.DBA.RDF_QUAD (P,S,O,G);
CREATE BITMAP index RDF_QUAD_SOPG on DB.DBA.RDF_QUAD (S,O,P,G);
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