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Posted to dev@jena.apache.org by "Andy Seaborne (Commented) (JIRA)" <ji...@apache.org> on 2012/01/30 23:19:10 UTC
[jira] [Commented] (JENA-205) Streaming results for CONSTRUCT
queries
[ https://issues.apache.org/jira/browse/JENA-205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13196477#comment-13196477 ]
Andy Seaborne commented on JENA-205:
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Personally, I'd go for Iterator<Triple>. Statements are tied to model; instead, provide a stream of things that are not tied to models AKA triples (and quads if we extend CONSTRUCT to have GRAPH like SPARQL Updates).
I also thing that making it distinct should be left out or at most optional. This is a low level interface.
N-triples is easy to stream out, as is Turtle. RDF/XML is hard enough to warrant not bothering with for now. I think that Turtle will quickly displace RDF/XML.
For Fuseki, a trick would be to stream back triples with duplicates - it's still legal RDF in all serializations to have duplicates. Then the server is not burdened.
> Streaming results for CONSTRUCT queries
> ---------------------------------------
>
> Key: JENA-205
> URL: https://issues.apache.org/jira/browse/JENA-205
> 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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