[redland-dev] Querying using SPARQL - misc questions

[Anahide Tchertchian]

> RDF literals cannot have both a language and a datatype, it's an
> either/or.

Ok, thanks for pointing that out, I didn't know.
So what should I understand about this constraint? Are literals without
a datatype considered to be strings, and only strings can have a
language set? (?)

> It seems having tried it out, that Redland's APIs allow both, when it
> shouldn't:

Yes, and I guess that's why I made this mistake.

>>2. I have a use case where I "clean" the graph deleting literal nodes
>>that where found thanks to a query. How come I cannot use nodes from the
>>result directly? (I have to create them again cloning the result nodes,
>>otherwise they're not found in the graph).
> 
> 
> Can you give a code example of what you mean by reuse?  They are new
> nodes returned and should be ok to use in any way you like.

By "reuse" I mean using a node from the results to create a statement 
that I will then delete from the graph.
It turns out I only have the problem with a mysql storage (and not 
memory), and I suspect this only happens with "invalid" literals (with 
both language and datatypes set).
I'll see if I still have the problem after correction.

> Anything with DISTINCT is suspicious as rasqal 0.9.10 (in redland 1.0.2)
> had bugs in that which I fixed in 0.9.11.

I already noticed that I could have strange behaviours using DISTINCT. 
Is it possible to make rasqal 0.9.11 work with other packages from 
redland 1.0.2?

Thanks a lot for your answers,
anahide.