Re: Issue adding Triples to Graph which has been added to a DatasetGraph.

[Dick Murray]

Hi Andy.

Thanks for the reply and just so I am sure I understand this... :-)

Looking at the Jena code for a SPARUL create graph <urn:test> against a
folder backed TDB store it gives the following stack;

Daemon Thread [Thread-24] (Suspended)
    GraphMem(GraphMemBase).<init>(ReificationStyle) line: 52
    GraphMem.<init>(ReificationStyle) line: 35
    Factory.createGraphMem(ReificationStyle) line: 50
    Factory.createDefaultGraph(ReificationStyle) line: 44
    Factory.createDefaultGraph() line: 38
    GraphFactory.createJenaDefaultGraph() line: 54
    GraphFactory.createDefaultGraph() line: 48

U4DefaultGraph$U4UpdateEngineWorker(UpdateEngineWorker).visit(UpdateCreate)
line: 140
    U4DefaultGraph$U4UpdateEngineWorker.visit(UpdateCreate) line: 369
    UpdateCreate.visit(UpdateVisitor) line: 58
    U4DefaultGraph$U4UpdateEngine.execute() line: 314
    UpdateProcessorBase.execute() line: 56
    U4DefaultGraph.graphSPARUL(U4HTTPDoRequestMessage) line: 1065
    U4DefaultGraph$5.go(Object) line: 857
    U4DefaultGraph$3.go(Object) line: 737
    U4DefaultGraph(U4DefaultNode).nodeMessageHandler(U4Message) line:
713
    U4DefaultNode$MessageHandler.run() line: 625
    ThreadPoolExecutor.runWorker(ThreadPoolExecutor$Worker) line: 1110
    ThreadPoolExecutor$Worker.run() line: 603
    Thread.run() line: 722

Specifically GraphFactory.createDefaultGraph() line: 48 is;

    /**
        Answer a memory-based Graph with the Standard reification style.
    */
    public static Graph createDefaultGraph()
        { return createDefaultGraph( ReificationStyle.Standard ); }

So Jena uses a memory based graph to fulfil the create graph request.

But uses add(Quad) to fulfil the insert data [into {iri}] {...} request as
detailed with the following stack.

DatasetGraphTxn(DatasetGraphTriplesQuads).add(Quad) line: 33
DatasetGraphTransaction(DatasetGraphTrackActive).add(Quad) line: 133
GraphStoreBasic(DatasetGraphWrapper).add(Quad) line: 72
UpdateEngineWorker.addToGraphStore(GraphStore, Quad) line: 484
U4DefaultGraph$U4UpdateEngineWorker(UpdateEngineWorker).visit(UpdateDataInsert)
line: 281

So I need to add the graph (as a empty mem based graph) to the TDB backed
dataset then add quads to the dataset..?

Dick.


On 29 November 2012 21:31, Andy Seaborne <a...@apache.org> wrote:

> On 29/11/12 21:24, Andy Seaborne wrote:
>
>>  > final Dataset d = TDBFactory.createDataset();
>>  > Node n = Node.createURI("urn:graph");
>>  > d.addGraph(n, GraphFactory.**createDefaultGraph());
>>
>> (sorry for the delay replying)
>>
>> I'm afraid that isn't going to work.  I suspect it should be an error.
>>
>
> It seems that the code adds in the contents of the graph into the dataset
> by copying over the triples - i.e. update before adding.
>
>         Andy
>
>
>
>> A TDB dataset is a triples+quad store.  You can't add an in-memory
>> storage-backed graph to a dataset backed by TDB.
>>
>> If you want a mixe dataset, you can create an in-memory dataset and add
>> in TDB backed graphs.
>>
>>      Andy
>>
>> On 28/11/12 20:32, Dick Murray wrote:
>>
>>> Hi all.
>>>
>>> I have an issue where triples which are added to a graph which has been
>>> added to a dataset are not visible in the dataset.
>>>
>>> However if I add the graph then add quads to the dataset with the quad
>>> graph node as the node used to add the graph the quads are visible.
>>>
>>> Is this expected?
>>>
>>
>