[Nepomuk] Problems with nepomuk server

[Sebastian Trueg]

I suppose the problem is sort of solved now that we know what the
problem is: Virtuoso does not support the boolean type. Thus, we use a
fake type which is properly converted in most Soprano methods. the only
situation which was not handled is query strings. Thus if one queries
for something like:

... ?r xxx:ppp "true"^^xsd:boolean .

it would not work since Virtuoso stores the fake type which is otherwise
hidden from the Soprano API.
This was no problem in 4.5 since we were not using boolean types in any
queries. But now we have nao:userVisible which highly improves query
performance but is a boolean property.

Thus, what we did is we added a very basic treatment of the incoming
queries which replaces the boolean type with the fake one. While this
works just fine there are still situations where we replace the wrong
things. One example would be literals that contain the text. So of
course the best solution would be to have Virtuoso support booleans.

Cheers,
Sebastian

On 08/25/2010 07:34 PM, George Goldberg wrote:
> On 25 August 2010 18:17, Sebastian Trueg <trueg at kde.org> wrote:
>> Hi George,
>>
>> On 08/25/2010 02:45 PM, George Goldberg wrote:
>>> 1) It starts virtuoso-t instance, then it starts another second
>>> virtuoso-t instance, which is quickly terminated.
>>
>> that is a weird special case when run the first time. I did not fix that
>> yet but it is not really a bug - more of an annoying side effect of the
>> automatic conversion for which I need to add special handling somewhere.
>>
>>> 2) There are a lot of the following lines:
>>> 2: [/opt/kde/bin/nepomukservicestub]
>>> "/opt/kde/bin/nepomukservicestub(27688)" Soprano: "SQLGetData for data
>>> lenght failed (iODBC Error: [iODBC][Driver Manager]Invalid cursor
>>> state)"
>>
>> do you also get all these messages when using 4.5?
>>
>> Apart from that I know that there is some problem with queries in trunk
>> at the moment. I am trying to track down the problem. It is weird,
>> however, that your main session works fine...
> 
> Actually, it doesn't. I think I must have got in a bit of a mess with
> different versions of things and so on... I've just cleaned out my
> trunk KDE install and rebuilt everything and queries don't work
> anywhere.
> 
> Let me know if there's anything I can do to help debug this issue (or
> if you have any ideas for a fix you'd like tested).
> 
> --
> George
>