On 04/05/12 07:33, Benjamin Nowack wrote:
On 5/3/12 11:03 PM, Andy Seaborne wrote:
Injecting in the right place can be quite cheap - the query string upto
that point, the syntax, and the query string after that point. There is
only one point to put variables in.
Our users are already struggling to write SPARQL 1.0 queries. Most query
templates are just a single GP with an occasional FILTER and/or REGEX
thrown in. They basically just write a query and then define which
variables are meant to be exposed by our API as parameters. We probably
can't ask them to inject the value placeholders themselves. The BINDINGS
approach worked in almost all cases.
... beware filters don't work as your users may expect.
This was Aidan's and Stephen's comments
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2012Mar/0018.html
http://lists.w3.org/Archives/Public/public-rdf-dawg-comments/2012Apr/0010.html
and motivated the change.
Do you want one set of values for the template in one query execution?
ARQ also allows for rewrite of parsed queries: a query can be rewritten
(either the abstract syntax tree or the SPARQL algebra) as replacing
specific variables by values prior to execution (this is even in the
public API). Discuss with your implementation of choice.
ARQ is our implementation of choice :) If it's as simple as adding some
parameters to the SPARQL API call (we only have HTTP access to the
backend), we'd have a perfect solution. Will look into that, thanks for
the hint!
It was on the list of features initially considered for work item with a
skew towards the compilation efficiency side of parametrized queries:
http://www.w3.org/2009/sparql/wiki/Feature:Parameters
nearby:
http://www.w3.org/2009/sparql/wiki/Feature:Query_by_reference
It didn't make the cut.
Andy
Cheers,
Benji
Andy
