Semantic Query Performance on LUBM Benchmark Query 2 (Doc ID 1142597.1)

Last updated on FEBRUARY 08, 2017

Applies to:

Oracle Spatial - Version: 11.2.0.1 and later   [Release: 11.2 and later ]
Information in this document applies to any platform.

Symptoms

In the process of evaluating Oracle’s RDF store capabilities in the Spatial product.
Trying to reproduce Oracle’s LUBM tests (http://www.oracle.com/technology/tech/semantic_technologies/htdocs/performance.html)
The performance of some queries are not close to the benchmark results.

System stats are:

- Dual quad core Xeon 3.0 Ghz processors (all allocated to the Oracle instance)
- 32 Gigs of Memory
- Storage: 750 Gig SATA disk
- Oracle 11gR2 (11.2.0.1) database with the following settings:
o pga_aggregate_target=12G
o sga_target=10112M
o filesystemio_options=”SETALL”
o db_file_multiblock_read_count=128
o db_block_size=8192
- We’ve added the following indexes via “ADD_SEM_INDEX”:
o CPSOM
o PS
o SCPM


Working with LUBM50 ontology in a model with 6.8 million triples and created entailments using OWLPRIME plus the new inference rules in 11.2 for an additional 5.4 million triples

Also have loaded up the DBPEDIA ontology in another model (this contains 196 million triples).

Query 2 from LUBM tests:

Q2: PREFIX ORACLE_SEM_FS_NS: <http://oracle.com/semtech#PLAIN_SQL_OPT=T> select ?x ?y where { ?x rdf:type lubm:GraduateStudent . ?y rdf:type lubm:University . ?z rdf:type lubm:Department . ?x lubm:memberOf ?z . ?z lubm:subOrganizationOf ?y . ?x lubm:undergraduateDegreeFrom ?y }


Q2: 5961 ms (versus 750 ms from published results)

Cause

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