Most vendors appear to be implementing their own as extensions. There is "ORDER_BY" in SPARQL. Threads I've read suggest its no so clean a mapping what a MIN or MAX URI might be, while COUNT should be fairly straight forward.
On a side note, I tracked allot of the development of XPath/XSLT and in that realm, extensions played a heavy part in the evolution of what functions or aggregates were most popular in the language. XSLT 1.1 had the EXSLT project (http://www.exslt.org/) defining extensions like this. Then XSLT 2.0 absorbed them into the standard. I think it wise of you to use whatever is most efficient directly on Sesame this time. -Mark On Feb 10, 2008, at 3:08 PM, David Huynh wrote: > That's very, very unfortunate. Do you know why those aggregate > functions > are not supported? > > Without aggregation performed at the source of the data, more data > than > necessary has to be transfered over to the sink. The larger the > data set > (the more useful aggregation is), the larger the transfer. The lack of > support for aggregation pretty much cripples any advanced browsing > functionality on top of SPARQL data sources. > > The first draft of SPARQL was in October 2004 [1]. I remember > informally > suggesting adding aggregate functions to it in Summer/Fall 2006. > > David > [1] http://www.w3.org/TR/2004/WD-rdf-sparql-query-20041012/ > > Brian Caruso wrote: >> The 2008 SPARQL recommendation definitely doesn't support COUNT >> and I don't >> think it supports MIN, MAX or what you would think of as a SQL style >> GROUP BY. >> >> >> David Huynh wrote: >> >>> Right now server-side Backstage formulates its queries to the >>> triple store by putting together Sesame "query algebra trees". If >>> SPARQL >>> is as expressive as Sesame's query algebra (supporting GROUP, COUNT, >>> MIN, MAX), then it shouldn't be hard to swap in a SPARQL end point >>> >>> >> _______________________________________________ >> General mailing list >> [email protected] >> http://simile.mit.edu/mailman/listinfo/general >> > > _______________________________________________ > General mailing list > [email protected] > http://simile.mit.edu/mailman/listinfo/general _______________________________________________ General mailing list [email protected] http://simile.mit.edu/mailman/listinfo/general
