[redland-dev] querying using ruby+sparql

[Dave Beckett]

On Tue, 2005-08-30 at 10:42 +0100, Eyal Oren wrote:
> Hi,
> 
> I've got two questions:
> 
> I'm using the cvs version of redland and ruby-bindings. When I'm querying
> (SPARQL) using roqet or ruby-bindings the 'distinct' keyword seems to be
> ignored. When I'm querying on librdf.org/query 'distinct' seems to
> respected though. Am I noticing this correctly, and is librdf.org/query
> maybe using a newer version of redland?

It's using a CVS version of rasqal which does implement DISTINCT.

> Performance-wise, it is better to query using SPARQL or using the model
> API? I guess this depends on the query, but for example if I just retrieve
> the set of outgoing predicates from a subject?  (I wanted to benchmark
> this, but since the 'distinct' doesn't work, the comparison is not really
> fair).

Performance wise there's nothing in it.  Using a query language vs API
approach has the usual tradeoffs of power/flexibility.   The API doesn't
implement DISTINCT, so you'd have to do it yourself - just one example
where the query language can help you do some things easier.  There are
others for both the query and API approaches.

Dave