Stardog 3.0 can SERVICE be used to copy data?

[Bram]

Hi,

I'm glad to see that there are a lot of usefull new functionality in stardog 3.0. Great work!

Is it possible to use the SERVICE statement to copy certain triples to the data store? I know that it is probably not intended to be used in this way since the data should be most accurate in it's own endpoint. It might be useful if the endpoint is an abstraction layer above a relational database and generating/calculating the triples is a slow process.

Do you use the VALUES statement for federated query optimization?

With kind regards
Bram

[Michael Grove]

On Thu, Apr 9, 2015 at 3:48 AM, Bram <bgad...@intec.ugent.be> wrote:

Hi,

I'm glad to see that there are a lot of usefull new functionality in stardog 3.0. Great work!

Thanks.

 

Is it possible to use the SERVICE statement to copy certain triples to the data store? I know that it is probably not intended to be used in this way since the data should be most accurate in it's own endpoint. It might be useful if the endpoint is an abstraction layer above a relational database and generating/calculating the triples is a slow process.

Are you asking if a read query can modify the endpoint associated with the SERVICE? 

 

Do you use the VALUES statement for federated query optimization?

No.

Cheers,

Mike

 

With kind regards
Bram

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[Bram]

Hi Michael,

As I see it the SERVICE keyword allows you to execute SPARQL queries on a remote endpoint and join them with other endpoints or your local RDF database.

E.g. the example from the recommendation where the local RDF database contains information regarding persons and the remote endpoint contains information regarding who knows who.

In our case the remote endpoint is just an abstraction layer that converts SQL queries to RDF triples. The execution of these queries might be rather slow and the information behind this might not change a lot but it might be resolved more frequently. So it might be useful if we could use the stardog triple store to cashe these results (e.g. periodically) and then query them more frequently locally.

I hope this makes sence.

With kind regards
Bram


Op donderdag 9 april 2015 09:48:40 UTC+2 schreef Bram:

[Zachary Whitley]

Follow on question about the SERVICE statement. 

Does the service statement pass along the rewritten query when using inferencing or does it simply pass along the query as written?

I think Bram might have been asking if you can use SERVICE in an Update query. ( the standard only specifies service with select queries) 

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[Michael Grove]

On Thu, Apr 9, 2015 at 7:12 AM, Bram <bgad...@intec.ugent.be> wrote:

Hi Michael,

As I see it the SERVICE keyword allows you to execute SPARQL queries on a remote endpoint and join them with other endpoints or your local RDF database.

E.g. the example from the recommendation where the local RDF database contains information regarding persons and the remote endpoint contains information regarding who knows who.

In our case the remote endpoint is just an abstraction layer that converts SQL queries to RDF triples. The execution of these queries might be rather slow and the information behind this might not change a lot but it might be resolved more frequently. So it might be useful if we could use the stardog triple store to cashe these results (e.g. periodically) and then query them more frequently locally.

That's a function that should be handled by the SERVICE.  Stardog would have no visibility into the lifecycle of the data in the SERVICE, so no way to invalidate it's cache, or even to know if things should be cached.

Cheers,

Mike

 

I hope this makes sence.

With kind regards
Bram


Op donderdag 9 april 2015 09:48:40 UTC+2 schreef Bram:

Hi,

I'm glad to see that there are a lot of usefull new functionality in stardog 3.0. Great work!

Is it possible to use the SERVICE statement to copy certain triples to the data store? I know that it is probably not intended to be used in this way since the data should be most accurate in it's own endpoint. It might be useful if the endpoint is an abstraction layer above a relational database and generating/calculating the triples is a slow process.

Do you use the VALUES statement for federated query optimization?

With kind regards
Bram

[Michael Grove]

On Thu, Apr 9, 2015 at 7:14 AM, Zachary Whitley <zachary...@gmail.com> wrote:

Follow on question about the SERVICE statement. 

Does the service statement pass along the rewritten query when using inferencing or does it simply pass along the query as written?

It passes them along as written.

afaik, there's nothing regarding SERVICE in the entailment regimes, so there's no clear right answer here.  We might change this behavior in the future.

Cheers,

Mike