GRAPH { OPTIONAL { } } behaves differently to OPTIONAL { GRAPH { } }
Sorry for the storm of issues :)
Perhaps this is compliant with the standard, but it seems counterintuitive that this returns results...
$ tracker3 sparql --dbus-service=org.freedesktop.Tracker3.Miner.Files -q 'SELECT ?file ?created { GRAPH tracker:Pictures { ?urn nie:isStoredAs ?file } . OPTIONAL { GRAPH tracker:FileSystem { ?file nfo:fileCreated ?created } } } LIMIT 1'
Results:
file:///home/sam/myfile
...while this does not...
$ tracker3 sparql --dbus-service=org.freedesktop.Tracker3.Miner.Files -q 'SELECT ?file ?created { GRAPH tracker:Pictures { ?urn nie:isStoredAs ?file } . GRAPH tracker:FileSystem { OPTIONAL { ?file nfo:fileCreated ?created } } } LIMIT 1'
Results:
None