2009/7/13 Georgi Kobilarov <[email protected]>:
> Hi John,
>
> it is true that the pagelinks dataset has not been loaded into the
> dbpedia.org/sparql instance. We did load it once, but most Linked Data
> and Sparql clients struggled with the very large result sets. For
> example, DESCRIBE http://dbpedia.org/resource/United_States would result
> in more than 300k triples due to the pagelinks (in particular because of
> inbound links)
>
> So we decided to only provide that dataset for download, but don't load
> it. I think it would be possible to provide a different rdf instance
> containing the pagelinks as well, but for the moment you'd have to load
> that dataset into your own repository.

In any very highly linked dataset you will find that DESCRIBE
behaviour implemented to retrieve both subject and object triples will
pretty much fail because of this issue. It is a shame that the inter
article links in Wikipedia are so diverse that they aren't accessible
using Linked Data anymore... ;-) (Seriously though, it is actually a
shame that there is a barrier to accessing this information without
downloading the dataset yourself, and even then you have to explain to
others that they need to do it themselves also...)

If only there was a way to tell the DESCRIBE query to get subject
triples and any referenced blank nodes but ignore triples which would
only be included because the URI was the object, but sadly DESCRIBE
queries are specified to be vendor implemented so anything could
happen in the future with ones DESCRIBE query I guess? Do the triples
where the URI is the subject get retrieved before the more trivial
triples where the URI is the object?

Depending on the limits that are set you might also be unable to
actually retrieve all of the triples in cases like this even if you
did set up another endpoint just for pagelinks. The public dbpedia
endpoint is setup from memory so a client can't even use LIMIT and
OFFSET to get 300 thousand triples?

Cheers,

Peter

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