计算机科学论坛--哪位大虾能够提供关于Jena中基于rdf推理效率的资料？

贴子主题：哪位大虾能够提供关于Jena中基于rdf推理效率的资料？

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jena帮助文档里面写了：
RDFS implementation and performance notes
The RDFSRuleReasoner is a hybrid implementation. The subproperty and subclass lattices are eagerly computed and stored in a compact in-memory form using the TransitiveReasoner (see below). The identification of which container membership properties (properties like rdf:_1) are present is implemented using a preprocessing hook. The rest of the RDFS operations are implemented by explicit rule sets executed by the general hybrid rule reasoner. The three different processing levels correspond to different rule sets. These rule sets are located by looking for files "etc/*.rules" on the classpath and so could, in principle, be overridden by applications wishing to modify the rules.

Performance for in-memory queries appears to be good. Using a synthetic dataset we obtain the following times to determine the extension of a class from a class hierarchy:

Set #concepts total instances #instances of concept JenaRDFS XSB*
1 155 1550 310 0.07 0.16
2 780 7800 1560 0.25 0.47
3 3905 39050 7810 1.16 2.11

The times are in seconds, normalized to a 1.1GHz Pentium processor. The XSB* figures are taken from a pre-published paper and may not be directly comparable (for example they do not include any rule compilation time) - they are just offered to illustrate that the RDFSRuleReasoner has broadly similar scaling and performance to other rule-based implementations.

The Jena RDFS implementation has not been tested and evaluated over database models. The Jena architecture makes it easy to construct such models but in the absence of caching we would expect the performance to be poor. Future work on adapting the rule engines to exploit the capabilities of the more sophisticated database backends will be considered.


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