Thanks for your explanations. However, my problem is that
node.getLiteralValue() on the node returns an Integer Java object.
DatasetGraphTDB dataset = TDBFactory.createDatasetGraph();
dataset.add(new Quad(
Node.createURI("http://openjena.org";),
Node.createURI("http://openjena.org";),
Node.createURI("http://openjena.org";), Node.createLiteral(
"-628675214", null, XSDDatatype.XSDlong)));
Iterator<Quad> res =
dataset.findNG(Node.ANY, Node.ANY, Node.ANY, Node.ANY);
Quad quad = null;
while (res.hasNext()) {
quad = res.next();
System.out.println(quad.getObject().getLiteralValue().getClass());
}
dataset.close();
It prints:
class java.lang.Integer
Or the problem is that I use quad.getObject().getLiteralValue() as a
parameter of a method that expects a Java Long object because the
value that was initially stored was a Long:
myMethod((Long) quad.getObject().getLiteralValue())
Or I get a ClassCastException due to the fact that
quad.getObject().getLiteralValue() returns an Integer.
Indeed, it is not possible to store a full Long (128 bits) as a typed
literal (due to the fact that numbers are encoded into 56 bits).
Hence, I have to store it as a non-typed literal and to parse it
manually but it also means that I cannot apply any method specific to
numbers on that field from a SPARQL query. That's why I was thinking
it is an issue :(
Laurent
On Wed, Jul 20, 2011 at 11:45 AM, Andy Seaborne
<[email protected]> wrote:
>
>
> On 19/07/11 14:56, Laurent Pellegrino wrote:
>>
>> Hi all,
>>
>> I am currently using a TDB instance with Quadruples (DatasetGraphTDB).
>> I insert some quads with a literal value which is typed with xsd:long:
>>
>> Node.createLiteral(Long.toString(myIdWhichIsAJavaLong), null,
>> XSDDatatype.XSDlong)
>>
>> At this step if I print the content to the standard output I get something
>> like:
>> "1900023546"^^http://www.w3.org/2001/XMLSchema#long
>>
>> Then, I execute a query that return the quadruples that contain the
>> literal values that were initially typed as xsd:long. When I print the
>> content to the standard output I get:
>> "1900023546"^^http://www.w3.org/2001/XMLSchema#integer
>>
>> Why does the datatype is not the same? Is it an issue?
>
> No - or at least, it shouldn't.
>
> xsd:long is a XSD 64 bit number
> xsd:integer is an arbitrary precision
>
> xsd:integer is a more general datatype than xsd:long (xsd:int is the 32 bit
> XSD integer).
>
> TDB stores numbers (integers, decimals, doubles), and dates and dateTimes
> and booleans, as their value, not as their lexical form. Actually, it
> encodes them into 56 bits (currently). If the number does not fit it is
> stores via the node table and lexical form.
>
> This saves space and makes queries involving FILTERs on values go faster.
> Much faster.
>
> See NodeId.inline(Node)
>
> Andy
>
