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From "Rob Vesse (Commented) (JIRA)" <>
Subject [jira] [Commented] (JENA-205) Streaming results for CONSTRUCT queries
Date Mon, 30 Jan 2012 22:35:10 GMT


Rob Vesse commented on JENA-205:

Streaming RDF/XML is not that hard if you are willing to either have very verbose output i.e.
a <rdf:Description> element per triple or to do some limited buffering and write out
in small batches.

You'd just have to be careful that you always add rdf:nodeId where blank nodes are involved
so that you don't rely on anonymous identifiers at all.

I'd very much like to see a streaming API for this as I have at least one piece of code where
I want that capability and haven't had the time to try and implement it myself yet.  Iterator<Triple>
would be my preference as well and I agree that doing the distinct on the server is unnecessary.
> Streaming results for CONSTRUCT queries
> ---------------------------------------
>                 Key: JENA-205
>                 URL:
>             Project: Jena
>          Issue Type: Improvement
>          Components: ARQ, Fuseki
>            Reporter: Stephen Allen
>            Assignee: Stephen Allen
>            Priority: Minor
> It would be useful to have CONSTRUCT queries that streamed results.  An additional method
on QueryExecution that returned an Iterator<Statement> (or something similar to that
[1]) would provide the necessary access.
> Implementationwise, the application of Bindings to the CONSTRUCT template is already
streaming, we would simply need to perform a distinct operation on the Triples that are created.
 We could use a DistinctDataNet to get semi-streaming with spill-to-disk functionality.
> Additionally, for this to be useful for Fuseki, we also need an RDF/XML serializer that
can operate on an Iterator<Statement> instead of a Model.
> [1] Prefix mappings would probably be nice for serializers that consume this iterator.

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