Re: DBLP Sparql Endpoint

seems like there is some kind of server side config limit


2014-04-04 15:32 GMT+02:00 Wetz Peter <peter.wetz@tuwien.ac.at>:

>  Hi!
>
>
>
> Thanks for your detailed reply and suggestions.
>
>
>
> But look at this query, which proves that there are indeed authors
> starting with ‘B’ at this endpoint:
>
>
>
> SELECT DISTINCT * WHERE {
>
> ?a a foaf:Agent .
>
> ?a foaf:name ?n .
>
> FILTER (?n = "Bertram Poettering")
>
> }
>
> LIMIT 10
>
>
>
> I dont know, why the REGEX queries do not return this result.
>
>
>
> for my example above (and according to your suggestion) the following
> query should also have the same result as above, but it hasn’t:
>
>
>
> SELECT DISTINCT * WHERE {
>
> ?a a foaf:Agent .
>
> ?a foaf:name ?n .
>
> FILTER  regex(?n, "bertram","i")
>
> }
>
> limit 10
>
>
>
> to me it seems as if the REGEX and String-functions only operate on a
> subset of the endpoint, i.e. on authors starting with an “A”. Why it is
> like that, i don’t know.
>
>
>
> Best,
>
> Peter
>
>
>
> *Von:* Saud Al-Jaloud [mailto:saud.aljaloud@gmail.com]
> *Gesendet:* Freitag, 04. April 2014 13:04
>
> *An:* Wetz Peter
> *Cc:* public-lod@w3.org
> *Betreff:* Re: DBLP Sparql Endpoint
>
>
>
>
>
> Hi,
>
>
>
> It's alway worth trying the query without the filter just to make sure of
> what to expect from regex.
>
>
>
> Or, negate the first regex like:
>
>
>
> SELECT DISTINCT * WHERE {
>
>
>
> ?a a foaf:Agent .
>
>
>
> ?a foaf:name ?n .
>
>
>
> FILTER  regex(?n, '^[^a]', 'i')
>
>
>
> }
>
>
>
> You will see that names that don’t start with an 'a' are like these:
>
>
>
> "(Max) Zong-Ming Cheng”
>
> "Á. B. Nagy"
>
>
>
> This means that there are no names start with 'b’. That’s why you got no
> results.
>
>
>
>
>
> If you are just searching for names, why not just write like this:
>
>
>
> SELECT DISTINCT * WHERE {
>
>
>
> ?a a foaf:Agent .
>
>
>
> ?a foaf:name ?n .
>
>
>
> FILTER  regex(?n, ‘b', 'i')
>
>
>
> }
>
>
>
> This above query will match any ‘b' character at any position. Or write
> more specific regex to match a position.
>
>
>
> Also, as suggested, other functions from SPARQL 1.1 like : STRSTARTS or
> CONTAINS would be, in principles, more efficient, but this would depend if
> the sparql engine is compatible with 1.1.
>
> I might be wrong but it seems not working on this endpoint so far.
>
>
>
> Cheers,
>
>
>
> Saud.
>
>
>