Hi Gary,
Construct statements make a graphs of triples representing information.
Construct statements can be used to manipulate, subset, and create new
data derived from existing data. Temporal and sequential information
being important things in this world, it would make perfect sense to be
able to do a ORDER BY on a construct statement so that connecting
triples can be generated to make linked lists of ordered information.
The problem is that there is no way to reference the prior/next solution
of the where clause in the construct statement to create the appropriate
triple pattern. Triple/quad stores do order information in that
triples/quads are indexed by their SPOG components to allow for faster
processing of graph patterns. Although what I am looking for could be
achieved in code, it would be beneficial to add a SPARQL feature
allowing the referencing of a prior/next solution. The use cases exist
and I don't see it being particularly difficult to implement -imho. - Erich
Erich Bremer
http://www.ebremer.com
On 10/17/12 10:22 AM, Gary King wrote:
Hi Erich,
There doesn't seem to be anyway to create a SPARQL construct statement like the
following:
I believe that the reasoning is that CONSTRUCT makes a _set_ of triples and
sets don't have an order. I.e., a triple-store is an unordered collection and
that it what CONSTRUCT constructs :-).
but I did not get anything that would work or seem remotely efficient. If this
is the case, why have order by in a construct statement at all if one cannot
capture this information as triples?
The ORDER clause in your example is essentially a no-op. Obviously, however, it
would be important if you also had a LIMIT.
HTH,
--
Gary Warren King, metabang.com
Cell: (413) 559 8738
Fax: (206) 338-4052
gwkkwg on Skype * garethsan on AIM * gwking on twitter
