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From Olivier Grisel <>
Subject Re: Do Stanbol have a global SPARQL endpoint?
Date Fri, 18 Mar 2011 13:30:30 GMT
2011/3/18 Enrico Daga <>:
>> I am sure they would appreciate to review patches should you want to
>> implement those improvements.
> Actually it looks like named graphs are supported.

Ok great.

> Thank you for the
> analysis, I've seen it in the clerezza dev list.
> About the performance issue (I didn't get this because of a very
> limited dataset), this is only a problem of the TDB triple store, if I
> understood correctly, and should not happen with other storage, such
> sesame, right?

It will happen on any other triple stores since currently the sparql
engine talks to the store through a set of generic clerezza wrappers
for the jena classes (TcDataset, JenaGraphAdaptor and so on).

This way you can use the jena sparql engine (ARQ) on a store that does
not support sparql by going through the clerezza wrapper: however when
the store is able to perform sparql queries optimization by itself,
the jena sparql does not see it and uses instead a naive iterator /
filtering strategy that works everywhere albeit without using any
indexing optimization provided by the store (and will furthermore put
a high pressure on the GC with the collection of many clerezza
transient wrapping objects).

Olivier -

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