tarql should support named graphs

[VladimirAlexiev]

to @cygri, cc @rdstn @andrecastro0o
For significant Update scenarios, it's very useful to have data organized by Named Graph.

Eg to implement CrunchBase incremental updates, it makes sense to have a named graph per record. Eg for organizations.csv:

• instead of Turtle

<org/(uuid)> a cb:Organization;
  cb:name "(name)";
  ...
  # empty newline

• I want TRIG:

graph <graph/organizations/(uuid)> {
  <org/(uuid)> a cb:Organization;
    cb:name "(name)";
    ...
    # empty newline
}

• plus a SPARQL update:

clear <graph/organizations/(uuid)>

As @jindrichmynarz reported, SPARQL 1.1 cannot produce named graphs with CONSTRUCT: w3c/sparql-dev#31.

Is there a chance for TARQL to implement some workaround?
TARQL is based on Jena, so @afs is there a chance Jena can implement this before it's standardized in SPARQL 1.2? I.e. expedite this issue and have a reference implementation for the others to follow?

[VladimirAlexiev]

@jindrichmynarz and @afs, I'm an idiot: Jindrich wrote

Apache Jena already allows to CONSTRUCT named graphs (https://jena.apache.org/documentation/query/construct-quad.html).

So we'll test it with TARQL

[afs]

For portability, TARQL could generate SPARQL Updates (INSERT DATA etc).

[rdstn]

Tested with TARQL, looks like it doesn't work, at least on the version I treid with:

org.apache.jena.query.QueryParseException: Encountered " "graph" "GRAPH "" at line 37, column 4.

[afs]

If you look at the stacktrace, it'll say where in TARQL. TARQL might choose strict SPARQL 1.1 and CONSTRUCT/GRAPH is a syntax extension.

A quick search of the code found TarqlParser.java and TarqlQuery.java, which has a comment it is a port from Jena2. All that is much simpler these days.