HI Mohammed,
> i ran a simple query
>
> select ?Company where {
> ?Company rdf:type dbo:Company.
>
> }
>
> i got the output but it does not contain renowned companies like google,
> microsoft
> why is it so
The SPARQL endpoint at http://dbpedia.org/sparql has a max result rows setting
of 10.000 records on any query, but there are much more subjects with this
property/value combo as per:
select count district ?Company where { ?Company rdf:type dbo:Company. }
which results in
call-ret 0
64255
When you actually use curl on your query you get the following information
returned:
$ curl -I
'http://dbpedia.org/sparql/?default-graph-uri=http%3A%2F%2Fdbpedia.org&query=select++%3FCompany+where+%7B+%0D%0A%3FCompany+rdf%3Atype+dbo%3ACompany.%0D%0A%7D&format=text%2Fhtml'
HTTP/1.1 200 OK
Date: Fri, 08 Jan 2016 16:03:09 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 1331298
Connection: keep-alive
Vary: Accept-Encoding
Server: Virtuoso/07.20.3215 (Linux) i686-generic-linux-glibc212-64 VDB
X-SPARQL-default-graph: http://dbpedia.org
X-SPARQL-MaxRows: 10000
Expires: Fri, 15 Jan 2016 16:03:09 GMT
Cache-Control: max-age=604800
Accept-Ranges: bytes
Where the X-SPARQL-MaxRows header indicates that the results is truncated.
To resolve this limitation, the dbpedia endpoint can be called using a paging
mechanism using the OFFSET XXX LIMIT YYY mechanism like this:
select ?Company where { ?Company rdf:type dbo:Company. } OFFSET 0 LIMIT
10000
select ?Company where { ?Company rdf:type dbo:Company. } OFFSET 10000
LIMIT 10000
…
…
…
select ?Company where { ?Company rdf:type dbo:Company. } OFFSET 60000
LIMIT 10000
Note that other endpoints may have different restrictions.
Patrick
---
Patrick van Kleef
Program Manager
OpenLink Software
http://www.openlinksw.com/
http://twitter.com/openlink/
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