SWI-Prolog for the semantic web

Re:SWI-Prolog for the semantic web by kendallgclark on Monday September 29, 2014 @02:07PM (#8384185)

SPARQL is PSPACE-complete. Worst case complexity and "fast in practice" aren't really the same thing at all. I suspect average case complexity for SPARQL is much better, which is backed up by several reasonably peformant implementations.

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Re:SWI-Prolog for the semantic web by rspeer on Monday September 29, 2014 @09:08PM (#8386253)

What are these reasonably performant implementations? Have you tried them with a billion edges?

Also, if your data store is "fast in practice" but has worst cases that are PSPACE-complete, how do you prevent worst-case queries from DOSing it?

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Re:SWI-Prolog for the semantic web by kendallgclark on Tuesday September 30, 2014 @12:29PM (#8389147)

Well, I'm a vendor in the space so I like my implementation: http://stardog.com/ -- and yes we've "tried it" with 10s of billions of edges.

Worst cases are prevented from DOSing by having query management features like auto-killing queries that run too long, etc.

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