rdf_unload_graph/1 does not work in snapshots

[wouterbeek]

:- use_module(library(semweb/rdf11)).

test1 :-
  rdf_assert(a, a, a, a),
  rdf_transaction(test2, _, [snapshot(true)]).

test2 :-
  rdf_assert(b, b, b, b),
  forall(rdf_graph(G), write(G)), nl,
  forall(rdf_graph(G), rdf_unload_graph(G)),
  forall(rdf_graph(G), write(G)), nl.

Running ?- test2. works as expected, but running ?- test1. does not unload graphs a and b.

[wouterbeek]

This is not so much a bug as an inherent limitation of the current triple store implementation. Access to graphs from within a snapshot can be supported once graphs are added to the API.