<div class="gmail_quote">On Mon, Feb 28, 2011 at 8:32 AM, Sebastian Trüg <span dir="ltr"><<a href="mailto:trueg@kde.org" target="_blank">trueg@kde.org</a>></span> wrote:</div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div><div></div><div>On 02/27/2011 02:32 PM, Ignacio Serantes wrote:<br>
> Hi!<br>
><br><br>
</div></div>That is why I wrote the query API. It handles all that for you and is<br>
optimized. There is no need for you to try to solve all the SPARQL<br>
problems again.<br></blockquote><div><br></div><div>I will add support to API in my query system so all this questions will be solved analyzing sparql queries created with the API.</div><div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>> But the really big problem is with relation ontologies like nao:hasTag.</div><div>
> In this particular case query is "?x nao:hasTag ?y . ?y nao:identifier<br>
> ?z . FILTER(?z)", so you need a inner join and you do the real filter in<br>
> nao:identifier but this is not applicable to all relations. Some light<br>
> about this stuff are welcome.<br>
<br>
</div>Actually the query should look like this:<br>
?r nao:hasTag ?t . ?t nao:prefLabel ?l . ?l bif:contains "foobar" .<br>
And that is why I can only stress: use the query API. This is why I<br>
wrote it. :)<br></blockquote><div><br></div><div>Yes, this was my first approach but when I found how to obtain identifier and I prefer to use it for unicode security and because identifier looks like a more generic property than prefLabel. In my test results sets are the same so I continue to use identifier.</div>
<div><br></div><div>About bif:contains, I do some test with filter() and bif:contains and I found that the second has penalty costs. I wrote the same query with both versions and found that results are always fast using filter() so I stop using bif:contains. Probably this was casual but, for precaution I write my builder using Filter().</div>
<div><br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Cheers,<br>
Sebastian<br>
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</blockquote></div><br><br clear="all"><br>-- <br>Cheers,<div>Ignacio</div><div><br></div><br>