Re: Query a Property Table using SPARQL

[Andy Seaborne]

On 27/08/15 07:16, Kim A. Jakobsen wrote:
On Wed, 26 Aug 2015 at 21:15 Andy Seaborne <a...@apache.org> wrote:
On 26/08/15 10:24, Kim A. Jakobsen wrote:
Hi

I have created a property table and I would like to query it using
SPARQL.
My code looks as follows:

PropertyTable propertytable = new PropertyTableArrayImpl(1, 1);
Column something = propertytable.createColumn(NodeFactory.createURI("
http://example.org/"; + "something"));
Row row = propertytable.createRow(NodeFactory.createURI("
http://example.org/";
+ "apple"));
row.setValue(something, NodeFactory.createLiteral("JOHN"));

How do I query the property table?

Hi there,

You can make the property table appear as an RDF graph with

GraphPropertyTable

and make that a model

ModelFactory.createModelForGraph
if you want to.

You can query it with SPARQL or the RDF API.

         Andy


Additionally then I would also like to make my property table persistent,
i.e. save it to the disk.
As fare as I know then it is only possible to save it as a CSV file, is
there any other options?

You can write the RDF graph.

  I suspect that if I simply write the model to the disk it will save it in
a statement table and not in a property table, how does it actually work?

It will be an RDF graph - not a CSV file.  I was assuming you want to 
work with CSV data as RDF but it sounds like you have a different objective.

I would like to play around with different indexes for the property table
but I do not know how much is implemented in Jena already.

You'll have to look in the code for that.  It's all in the jena-csv module.

        Andy


Thanks
Kim

In fact, what might work for you is to convert the CSV file with
riotcmdx.csv2rdf and work in RDF from there on.

         Andy


Regards
Kim A. Jakobsen