On 2014-07-16 10:34, Alexey Zakhlestin wrote:
>
> On 14 Jul 2014, at 17:37, Bart Vandewoestyne <bart.vandewoest...@telenet.be>
> wrote:
>
>> Our problem is the following: we observed that certain of our SPARQL
>> queries have subqueries (that return IDs) that run rather slow (because
>> of a slow bif:contains full-text-search). We therefore
>> 'migrated'/'copied'/'flattened' some of our data to another
>> technology/database/store that allows for faster textual search.
>> Querying this database results in a list of IDs, and these IDs are then
>> 'injected' in a SPARQL query (we simply create a SPARQL query string
>> with all these IDs in the FILTER command).
>>
>> Apparently, we are limited to filtering 4094 IDs and I don't see a way
>> to overcome this if the subquery returns more. Could there be a way to
>> work-around this limitation at SPARQL level?
>
> Couple of untested thoughts:
>
> 1. try to use several IN() filters by joining them using OR
>
> FILTER(?id IN(1,2,3) or ?id IN(4,5,6))
>
> 2. use UNION to join result sets
>
> {
> … . FILTER(?id IN(1,2,3)
> }
> UNION
> {
> … . FILTER(?id IN(4,5,6)
> }
Getting back to my old question, I have another question :-)
Am I right if I say that using an expression like
?id IN(1,2,3)
is a Virtuoso-specific extension to the SPARQL standard?
I can't seem to find anything about IN() online at
http://www.w3.org/TR/rdf-sparql-query/#grammar nor
http://www.w3.org/TR/sparql11-overview/ but if my interpretation of the
grammar online at http://docs.openlinksw.com/virtuoso/rdfsparql.html is
correct, then according to rule [47] the use of IN() is a
Virtuoso-specific extension.
Can anybody confirm? And if this is indeed a Virtuoso-specific
extension, then what would be the most appropriate/efficient way to
rewrite a FILTER-statement of the form
FILTER (?id IN (1, 2, 3))
in a standard-conforming way?
Kind regards,
Bart
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