On 21/12/2016 17:07, Andy Seaborne wrote:
>
>
> On 21/12/16 13:13, George News wrote:
>> On 21/12/2016 13:46, Andy Seaborne wrote:
>>>
>>>
>>> On 21/12/16 12:23, George News wrote:
>>>> szQuery = "" + " PREFIX dc: <http://purl.org/dc/elements/1.1/>" + "
>>>> PREFIX foaf: <http://xmlns.com/foaf/0.1/>" + " SELECT ?graph ?who
>>>> ?mbox"
>>>> + " FROM NAMED <http://example.org/alice>" + " FROM NAMED
>>>> <http://example.org/bob>" + " WHERE " + " { \n" + " ?graph dc:publisher
>>>> ?who . " + " GRAPH ?graph { ?x foaf:mbox ?mbox . } " + " }";
>>>
>>> Take out the FROM NAMED.
>>>
>>> Adding FROM or FROM NAMED creates a view of the original data - in this
>>> case with just 2 named graphs. You don't want a view - you want the
>>> real thing.
>>>
>>> Andy
>>>
>>
>> But then, how can I define to search only in some graphs? I was planning
>> to have more than two in total, and only search on some of them.
>
> There are various ways
>
> 1/ Use FROM <urn:x-arq:DefaultGraph> to include the default graph in
> the view dataset.
Thanks a lot for that one. I didn't know how to access the default graph
in a SPARQL sentence.
> 2/ Make a union model and query that.
>
> 3/ Use GRAPH <g> in a query (when it is just one graph)
>
> 4/ Use GRAPH ?g {} FILTER( ... ?g ....) in a query (when it is just one
> graph)
>
> (They are not exactly equivalent. )
>
> The details of the usage will suggest a particular approach as will the
> total volume of data.
Great!! Just a last question: is it better to have many named graphs and
restrict queries to them or a union of some o them, or would it be
better to have just only one big graph?
I think the answer is quite straight ;) but just for curiosity.
Regards
Jorge
> Andy
>
>>
>> See you
>> Jorge
>>
>
