[Mulgara-dev] ITQL

[Paul Gearon]

On Sat, Jul 12, 2008 at 8:15 AM, David Wood <dwood at softwarememetics.com> wrote:
> The W3C is starting to think about SPARQL+ (again).  I will be
> reviewing the eventual contents of the org.mulgara.client.tql package
> for fodder :)

Certainly follow up on aggregates and subqueries. I believe that
aggregates are already on the agenda.

I also think that having the bindings for the variable "x" should not
be restricted to the list in FROM GRAPH when used in the expression:
  GRAPH ?x {...}

In TQL there are no pre-imposed bindings for "x" in the expression
".....IN $x". You can add these bindings, but if you don't, you'll get
every graph you know about. You can even get $x from another
constraint. While SPARQL allows you to get "x" from a constraint, it
is intersected with the list in FROM GRAPH.

However.....

Don't go copying trans(...) or walk(...).  I've never liked this
syntax (I invented it) and I now have something better. Andrae's query
transformation code now makes it possible to use the following instead
of trans(...):
  $x ns:ancestorOf $y .
  ns:ancestorOf rdf:type mulgara:TransitivePredicate

I like this, since it looks just like using owl:TransitivePredicate,
only it refers to extrinsic statements instead. It also means we don't
have to extend SPARQL to extend the functionality of our
implementation. We just define certain predicates to refer to
extrinsic statements.

Regards,
Paul Gearon