On 28/09/13 14:42, Michael Brunnbauer wrote:
Hello Andy,
On Sat, Sep 28, 2013 at 11:12:28AM +0100, Andy Seaborne wrote:
Inner part:
BIND ('X' as ?ep)
This is evaluated separately because BIND ends the graph pattern ?
Another question: If I do something like
?ep a void:sparqlEndpoint
SERVICE SILENT ?ep { ...
then ?ep is not bound if the federation fails. That a failure causes a match
with unbound variables is expected but that ?ep is also unbound in this case
surprised me. This is intended ?
Is it? In the latest version? Assuming ?ep a void:sparqlEndpoint
matches something in the local dataset
SERVICE SILENT ?ep --> failure
evaluates to the join identity (one row, no columns) and ?ep is unbound
in that. This joins with the eval of "?ep a void:sparqlEndpoint".
If not, please submit a JIRA with complete minimal example.
ARQ tries to evaluate using a different algorithm - you can try the
reference query engine (--engine=ref or call QueryEngineRef.register()
in code) which is a very simple, and hopefully dependable, bottom-up
materialising evaluation of a query. It does not scale.
Andy
Regards,
Michael Brunnbauer
