[Nepomuk] Some issues on current master

[Sebastian Trüg]

On 05/31/2012 11:13 AM, Marco Martin wrote:
> On Thursday 31 May 2012, you wrote:
>> On Thursday 31 May 2012, Sebastian Trüg wrote:
>>> please see if this patch fixes the issue.
>>>
>>> On 05/31/2012 10:24 AM, Marco Martin wrote:
>>>> On Thursday 31 May 2012, Marco Martin wrote:
>>>>> On Thursday 31 May 2012, Sebastian Trüg wrote:
>>>>>> which version of virtuoso are you using?
>>>>>>
>>>>>> And, yes, the virtuoso branch needs to be merged in kdelibs indeed.
>>>>>
>>>>> i tried on 2 different systems with 6.1.2 and 6.1.4, now i'm trying to
>>>>> install 6.1.5
>>>>
>>>> with 6.1.5 apparently there is the same issue of parse error (syntax
>>>> error at exists)
>>
>> now the query is actually executed, but a query like
>>
>> select distinct ?r ?reqProp1 where { { OPTIONAL { ?r
>> <http://www.semanticdesktop.org/ontologies/2007/01/19/nie#url> ?reqProp1 .
>> FILTER(bif:exists((select (1) where { ?r a [
>> <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#userVisible>
>> "true"^^<http://www.w3.org/2001/XMLSchema#boolean> ] . }))) . } }
>>
>> (similar to what the query api tends to generate now)
>> just spikes the cpu usage of virtuoso and will never finish
> 
> something like
> 
> select distinct ?r ?reqProp1 where {?r ?v1 ?v2 . FILTER(bif:exists((select (1) 
> where { ?r a [ 
> <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#userVisible> 
> "true"^^<http://www.w3.org/2001/XMLSchema#boolean> ] . }))) . }
> 
> seems to work.
> 
> however, with the query api if you do something like
> 
> m_query.addRequestProperty(Nepomuk::Query::Query::RequestProperty(NIE::url()));
> 
> to have some properties already in the result to minimize round-trips, the 
> generated query becomes as the one i put before,
>  select distinct ?r ?reqProp1 where { { OPTIONAL { ?r
>  <http://www.semanticdesktop.org/ontologies/2007/01/19/nie#url> ?reqProp1 .
>  FILTER(bif:exists((select (1) where { ?r a [
>  <http://www.semanticdesktop.org/ontologies/2007/08/15/nao#userVisible>
>  "true"^^<http://www.w3.org/2001/XMLSchema#boolean> ] . }))) . } }
> 
> with one filter clause inside each OPTIONAL block, and this seems to kill 
> virtuoso (6.1.5 on this machine now)

I think this is caused by the missing real pattern. Your query does not
contain any actual pattern. It looks as if you want to get all resources.

> Cheers,
> Marco Martin
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