Re: SPARQL and Subqueries

On 24/01/2008, Orri Erling <erling@xs4all.nl> wrote:

> For a second iteration of SPARQL, we propose aggregation and subqueries.

Yup, I reckon the former is essential and the latter highly desirable
for increased application of SPARQL.

> http://virtuoso.openlinksw.com/blog/

> where I present a sample of an extension for subqueries and aggregates.
>
> There is also a syntax sugar for abbreviating chains of joins.

I'm a little confused:

[[
We notice the pattern { ?ms+>tpcd:has_nation+>tpcd:has_region
tpcd:name 'EUROPE' } which is a shorthand for { ?ms tpcd:has_nation
?t1 . ?t1 tpcd:has-region ?t2 . ?t2 tpcd:has_region ?t3 . ?t3
tpcd:name "EUROPE" }
]]

The ?t variables don't seem to be available from the shorthand
version, and if you take them out of the example you have:

{ ?ms tpcd:has_nation [ tpcd:has-region [ tpcd:name "EUROPE" ]]] }

- which isn't exactly verbose. (I assume the extra has_region is a typo).

Am I missing something?

> Aside these, there is the issue of discovery and description.  We will
> implement a little database statistics  graph for distributed query
> optimization and data discovery. More on this later.

Looking forward to it.

Cheers,
Danny.

-- 

http://dannyayers.com