Thanks Ivan, this is way faster!
Best,
Dimitris
On Mon, Aug 12, 2013 at 9:35 PM, Ivan Mikhailov
<imikhai...@openlinksw.com>wrote:
> Hello Dimitris,
>
> I'd rephrase the query, magin the filter index-friendly:
>
> SELECT ?wiki, ?dbp, bif:datediff('second', xsd:DateTime(?extracted),
> now()) AS ?secondsAgo
> FROM <http://nl.dbpedia.org>
> WHERE {
> ?wiki foaf:primaryTopic ?dbp .
> ?dbp dcterms:modified ?extracted .
> FILTER ( ?extracted > bif:dateadd('minute', -10, now()))
> } order by desc (?extracted)
> LIMIT 30
>
> In this case the presence or the absence of the order by does not matter
> too much, because the query is way more straightforward: selective
> index-friendly filter first, and the selection could be ordered
> naturally via hot index used by the filter.
>
> Note also that if you know the datatype of an object literal, there's no
> need to write a cast like xsd:dateTime --- it can make an expression
> index-unfriendly even if it will always return the argument unchanged on
> your specific data.
>
> Best Regards,
>
> Ivan Mikhailov
> OpenLink Software
> http://virtuoso.openlinksw.com
>
> On Mon, 2013-08-12 at 18:48 +0300, Dimitris Kontokostas wrote:
> > Hi, I am experimenting with a new "latest updates" display for DBpedia
> > Live in Dutch where I get the list live from Virtuoso with javascript
> > http://live.nl.dbpedia.org/statistics/statistics.html
> >
> >
> > I am storing the timestamp of all the extracted item as a
> > dcterms:modified on the dbpedia resource and run the following query :
> >
> >
> > SELECT ?wiki, ?dbp, bif:datediff('second', xsd:DateTime(?extracted),
> > now()) AS ?secondsAgo
> > FROM <http://nl.dbpedia.org>
> > WHERE {
> > ?wiki foaf:primaryTopic ?dbp .
> > ?dbp dcterms:modified ?extracted .
> > FILTER ( bif:datediff('minute', now(), xsd:DateTime(?extracted)) <=
> > 10 )
> > } ORDER BY DESC(?extracted)
> > LIMIT 30
> >
> >
> > The problem is that the query is too slow and sometimes does not
> > return and the page looks empty
> >
> >
> > Is there a way I can change the query to speed it up or should i try
> > to get the update list outside virtuoso?
> >
> >
> > An average update on the Dutch Live server is 2-3 articles per second
> > but may also range from 0 to 10 at peaks, also note that we will port
> > this method to the English Live where the update frequency is higher.
> >
> >
> > Best,
> >
> > Dimitris
> >
> > --
> > Dimitris Kontokostas
> > Department of Computer Science, University of Leipzig
> > Research Group: http://aksw.org
> > Homepage:http://aksw.org/DimitrisKontokostas
> >
> ------------------------------------------------------------------------------
> > Get 100% visibility into Java/.NET code with AppDynamics Lite!
> > It's a free troubleshooting tool designed for production.
> > Get down to code-level detail for bottlenecks, with <2% overhead.
> > Download for free and get started troubleshooting in minutes.
> >
> http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk
> > _______________________________________________ Virtuoso-users mailing
> list Virtuoso-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/virtuoso-users
>
>
>
>
>
> ------------------------------------------------------------------------------
> Get 100% visibility into Java/.NET code with AppDynamics Lite!
> It's a free troubleshooting tool designed for production.
> Get down to code-level detail for bottlenecks, with <2% overhead.
> Download for free and get started troubleshooting in minutes.
> http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk
> _______________________________________________
> Virtuoso-users mailing list
> Virtuoso-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/virtuoso-users
>
--
Dimitris Kontokostas
Department of Computer Science, University of Leipzig
Research Group: http://aksw.org
Homepage:http://aksw.org/DimitrisKontokostas
------------------------------------------------------------------------------
Get 100% visibility into Java/.NET code with AppDynamics Lite!
It's a free troubleshooting tool designed for production.
Get down to code-level detail for bottlenecks, with <2% overhead.
Download for free and get started troubleshooting in minutes.
http://pubads.g.doubleclick.net/gampad/clk?id=48897031&iu=/4140/ostg.clktrk
_______________________________________________
Virtuoso-users mailing list
Virtuoso-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/virtuoso-users
