Pure-SPARQL migration of data from one endpoint to another?

Question

It looks like this question has been raised before, but subsequently deleted?!

For data in one SQL table, I can easily replicate the structure and then migrate the data to another table (or database?).

CREATE TABLE new_table
  AS (SELECT * FROM old_table);

SELECT *
INTO new_table [IN externaldb]
FROM old_table
WHERE condition;

Is there something analogous for RDF/SPARQL? Something that combines a select and an insert into one SPARQL statement?

Specifically, I use Karma, which publishes data to an embedded OpenRDF/Sesame endpoint. There's a text box on the GUI for the endpoint, so I can change it to a free-standing RDF4J, since RDF4J is a fork of Sesame.

Unfortunately, I get an error like invalid SPARQL endpoint from Karma when I put the address for a Virtuoso, Stardog or Blazegraph endpoint in the endpoint text box. I suspect it might be possible to modify and recompile Karma, or (more realistically), I could write a small tool with the Jena or RDF4J libraries to select into RAM or scratch disk space and then insert into the other endpoint.

But if there's a pure-SPARQL solution, I'd sure like to hear it.

I'm curious if you've tried such kind of approach and it's what you're looking for? https://stackoverflow.com/questions/10078966/multiple-sparql-insert-where-queries-in-a-single-request if not, perhaps at least it might get you going to the right direction — Evaldas Buinauskas, Jun 14 '17 at 17:36
Technically, `INSERT { ?s ?p ?o . } WHERE { ?s ?p ?o . };` such query should select every possible triple in database (`WHERE` clause) and insert should create them. This is answer to your question `Something that combines a select and an insert into one SPARQL statement?` But I guess you want to do more complex things just than that. — Evaldas Buinauskas, Jun 14 '17 at 17:45
great, can you show how I specify the source and destination endpoints? — Mark Miller, Jun 14 '17 at 17:46
That's something I wouldn't be able to answer, I haven't worked with RDF/SPARQL to that level :/ but this question seems to have some detail about reading from/inserting to remote destination. https://stackoverflow.com/questions/42615446/sparql-insert-data-from-remote-endpoint and looks quite promising. — Evaldas Buinauskas, Jun 14 '17 at 17:49
Yes, that solution works *at least* with Jena (via Fuseki 2.6.0) grabbing data from wikidata. I still have to try it with other sources and destinations. Thanks EvaldasBuinauskas and @AKSW — Mark Miller, Jun 14 '17 at 18:23

Jeen Broekstra · Accepted Answer · 2017-06-15T04:45:22.893

In SPARQL, you can only specify the source endpoint. Therefore, a partial pure-SPARQL solution would be to run the following update on your target triplestore:

INSERT { ?s ?p ?o } 
WHERE { SERVICE <http://source/sparql> 
        { 
           ?s ?p ?o
        }
}

This will copy over all triples from the (remote) source's default graph to your target store, but it doesn't copy over any named graphs. To copy over any named graphs as well, you can execute this in addition:

INSERT { GRAPH ?g { ?s ?p ?o } } 
WHERE { SERVICE <http://source/sparql> 
        { 
          GRAPH ?g {
           ?s ?p ?o
          }
        }
}

If you're not hung up on pure SPARQL though, different toolkits and frameworks offer you all sorts of options. For example, using RDF4J's Repository API you could just wrap both source and target in a SPARQLRepository proxy (or just use a HTTPRepository if either one is an actual RDF4J store), and then just run copy API operations. There's many different ways to do that, one possible approach (disclaimer: I didn't test this code fragment) is this:

  SPARQLRepository source = new SPARQLRepository("http://source/sparql");
  source.initialize();
  SPARQLRepository target = new SPARQLRepository("http://target/sparql");
  target.initialize();

  try (RepositoryConnection sourceConn = source.getConnection(); 
       RepositoryConnection targetConn = target.getConnection()) {
     sourceConn.export(new RDFInserter(targetConn)); 
  }

Great. The default graph insert does work for me in Fuseki. I'll try it with my other stores, plus the named graph insert and the RDF4J snippet later today. — Mark Miller, Jun 15 '17 at 10:59

Pure-SPARQL migration of data from one endpoint to another?

1 Answers1