ondisk not working

[luigi-asprino]

This query

PREFIX  fx:   <http://sparql.xyz/facade-x/ns/>

SELECT  *
WHERE
  { SERVICE <x-sparql-anything:location=https://sparql-anything.cc/example1.json,ondisk=/Users/lgu/Desktop/tmp>
      { ?s  ?p  ?o }
  }

gives

-------------
| s | p | o |
=============
-------------

After inspecting the code I discovered that in the case of ondisk set, the query has to indicate the graph to be queried.
We can ignore for a moment that the query is supposed to give the same result with and without the ondisk set, but this

PREFIX  fx:   <http://sparql.xyz/facade-x/ns/>

SELECT  *
WHERE
  { SERVICE <x-sparql-anything:location=https://sparql-anything.cc/example1.json,ondisk=/Users/lgu/Desktop/tmp>
      { GRAPH <https://sparql-anything.cc/example1.json#>
          { ?s  ?p  ?o }
      }
  }

raises an exception org.apache.jena.dboe.transaction.txn.TransactionException: Not in a transaction.

Probably, this is because the FacadeXOpExecutor doesn't start a READ transaction before executing the operation.

[luigi-asprino]

With this the OpExecutor starts a Read transaction before executing the query. I leave the issue open since I would like to avoid the user indicating the graph to be queried (as for the queries without ondisk property).

[justin2004]

oh, for on ondisk you must do graph ?g -- that is you can't query the union graph like you can with an in memory graph.
i put a comment in the code about it. i'll find it.

[justin2004]

here it is:
https://github.com/SPARQL-Anything/sparql.anything/blob/v0.8-DEV/sparql-anything-model/src/main/java/com/github/sparqlanything/model/BaseFacadeXGraphBuilder.java#L143-L150

[justin2004]

i tried to make ondisk behave just like in memory but it turned out that getUnionGraph() isn't implemented for the DatasetGraph used when you use a TDB2 on disk.

i almost opened an apache jena bug because i remember thinking it looks like it should be implemented.

[luigi-asprino]

I tried to set the global property symUnionDefaultGraph as true as suggested here but didn't work.
Then, I made the OpExecutor execute the query on the union graph (in case of ondisk set) and it seems to be working

[luigi-asprino]

Closed via 6a1b0e1

[luigi-asprino]

Doesn't work when passing arguments in the BGP.

[luigi-asprino]

Closed with 29b08b1