tbloader vs SPARQL INSERT - Why different behaviour with named graphs?

Question

There is a strange behaviour in the connection of the commandline tools of ARQ, TDB and Named Graphs. If importing data via tdbloader in a named graph it can not be queried

Answer 1

Try this query:

PREFIX : 
SELECT * { { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } }

and the output is

----------------------------
| s   | p   | o   | g      |
============================
|  |  |  |  |
|  |  |  | :      |
----------------------------

or try:

 tdbquery --loc DB --file Q.rq -results srj

to get the results in a different form.

The text output is makign things look nice but two different things end up as .

What you are seeing is that

tdbloader --desc tdb.ttl --graph data data.ttl

used data exactly as is to name the graph. But

INSERT DATA {GRAPH  {  .}}

does a full SPARQL parse, and resolves against the base URI, probably looking like file://*currentdirectory*.

When printing in text, URIs get abbreviated, including using the base. So both the original data (from tdbloader) and file:///path/data appear as .

PREFIX : 

gives the text output a different way to write it as :.

Finally try:

BASE 
SELECT * { { ?s ?p ?o } UNION { GRAPH ?g { ?s ?p ?o } } }

which sets the base URI to something no where near your data URIs so switching off nice formatting by base URI:

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