Hello Hugh,
I am relieved to learn that this is unexpected behaviour. Having to get
the order right for each query would be huge complication.
Yes, I am using the commercial release. It is version 6.4.3132.
I will try to log the execution plans for both queries and send them to
you personally.
Regards,
Frans
On 2-7-2013 22:33, Hugh Williams wrote:
Hi Frans,
This does look odd, what is the Virtuoso version being used ? Also you
indicate the data is hosted in a remote relational database in which
case I assume you are using the Virtuoso commercial release ?
It would be interesting to see the sparql_to_sql_text() output for
both queries to see how they differ, as detailed at:
http://docs.openlinksw.com/virtuoso/fn_sparql_to_sql_text.html
Best Regards
Hugh Williams
Professional Services
OpenLink Software, Inc. // http://www.openlinksw.com/
Weblog -- http://www.openlinksw.com/blogs/
LinkedIn -- http://www.linkedin.com/company/openlink-software/
Twitter -- http://twitter.com/OpenLink
Google+ -- http://plus.google.com/100570109519069333827/
Facebook -- http://www.facebook.com/OpenLinkSoftware
Universal Data Access, Integration, and Management Technology Providers
On 2 Jul 2013, at 09:00, Frans Knibbe | Geodan <[email protected]
<mailto:[email protected]>> wrote:
Hello,
I think I can share the specifics with the list. Here are two queries
that can be executed on http://lod.geodan.nl/sparql:
*Query A:*
select ?obs
from <http://lod.geodan.nl/cbs/gwb/>
where {
?obs rdf:type <http://purl.org/linked-data/cube#Observation> .
?gem rdfs:label "Amersfoort" .
?obs <http://lod.geodan.nl/cbs/gwb/area> ?gem .
}
*Query B:*
select ?obs
from <http://lod.geodan.nl/cbs/gwb/>
where {
?gem rdfs:label "Amersfoort" .
?obs rdf:type <http://purl.org/linked-data/cube#Observation> .
?obs <http://lod.geodan.nl/cbs/gwb/area> ?gem .
}
The difference is that in query B the first two triples in the WHERE
clause are switched. Query A returns one result, query B returns two.
I expect two results.
I think I should also note that the data source is a table in a
remote RDBMS. I can imagine that the effect would not occur if the
data were stored in a local table.
Regards,
Frans
On 1-7-2013 22:06, Todd DeLuca wrote:
Hi Frans,
I am fairly new to SPARQL too. I would be curious to see what
triple patterns you used to get these two different results.
Best,
Todd
On Mon, Jul 1, 2013 at 3:55 PM, Frans Knibbe | Geodan
<[email protected] <mailto:[email protected]>> wrote:
Hello,
I am a beginner with SPARQL. I have always been under the impression
that the order of triple patterns in the WHERE clause of a
SPARQL SELECT
query does not matter. But now I got an unexpected result from a
SPARQL
query issued to my Virtuoso 6 endpoint. The query contains three
triple
patterns in the WHERE clause. I expected a solution of two
triples, but
I only got one. But after switching two triples I did get the
expected
result. So changing the order changes the result.
Does this indicate a problem? Or do I have to get used to the
idea that
the order of the triple patterns in the WHERE clause does matter?
Thanks,
Frans
------------------------------------------------------------------------------
This SF.net <http://SF.net> email is sponsored by Windows:
Build for Windows Store.
http://p.sf.net/sfu/windows-dev2dev
_______________________________________________
Virtuoso-users mailing list
[email protected]
<mailto:[email protected]>
https://lists.sourceforge.net/lists/listinfo/virtuoso-users
--
Todd DeLuca
Scientific Programmer
Wall Lab, CBMI, Harvard Medical School
http://todddeluca.com <http://todddeluca.com/>
http://wall.hms.harvard.edu/
--
--------------------------------------
*Geodan*
President Kennedylaan 1
1079 MB Amsterdam (NL)
T +31 (0)20 - 5711 347
E [email protected]
www.geodan.nl <http://www.geodan.nl/> | disclaimer
<http://www.geodan.nl/disclaimer>
--------------------------------------
------------------------------------------------------------------------------
This SF.net <http://SF.net> email is sponsored by Windows:
Build for Windows Store.
http://p.sf.net/sfu/windows-dev2dev_______________________________________________
Virtuoso-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/virtuoso-users
--
--------------------------------------
*Geodan*
President Kennedylaan 1
1079 MB Amsterdam (NL)
T +31 (0)20 - 5711 347
E [email protected]
www.geodan.nl <http://www.geodan.nl> | disclaimer
<http://www.geodan.nl/disclaimer>
--------------------------------------
------------------------------------------------------------------------------
This SF.net email is sponsored by Windows:
Build for Windows Store.
http://p.sf.net/sfu/windows-dev2dev
_______________________________________________
Virtuoso-users mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/virtuoso-users
