Geospatial and XQuery?Michael Kay mhk at mhk.me.uk
Tue Oct 4 19:05:56 PDT 2005
Good point: though I don't think it proves that you need such functions in the core (standardized) language, only that you need the XQuery engine to be aware of the functions so that it can optimize them. Michael Kay http://www.saxonica.com/ Without a standard how would an XQuery optimizer know how to deal with a third-party geospatial function? Execution plans would differ drastically depending on the cost or absence of spatial indexes, etc. I recall seeing a sepecialized XQuery extension standard for text search. It seems like there's an opprotunity to do the same with geospatial data, especially if it was written w.r.t common XML geospatial data formats. -Kevin On 10/4/05, Martin Probst <http://xquery.com/mailman/listinfo/talk> wrote: Real-To: Martin Probst <http://xquery.com/mailman/listinfo/talk> Real-Cc: http://xquery.com/mailman/listinfo/talk <mailto:http://xquery.com/mailman/listinfo/talk> Hi, > If so, what would the geospatial functions look like in a query? > Have any of the XQuery or XML database products (commercial or open- > source) implemented geospatial functions ahead of the spec? If so, > what do these look like? X-Hive/DB is used by Galdos (http://www.galdosinc.com/) in Cartalinea. They did not need custom functions that much as fast range queries on XML attributes, e.g. to find certain specific elements that are within (in the spatial, not in the XML sense) a set of coordinates. So basically they needed fast range index lookups on XQuery, XPointer and XPath queries. I don't think there is a need for a standardisation on specific geospatial functions, especially as you can extend nearly every XQuery implementation with your own custom functions so you can use these custom functions as an adaptor-like wrapper around a library in e.g. Java. Martin _______________________________________________ http://xquery.com/mailman/listinfo/talk http://xquery.com/mailman/listinfo/talk <http://xquery.com/mailman/listinfo/talk> -------------- next part -------------- An HTML attachment was scrubbed... URL: http://xquery.com/pipermail/talk/attachments/20051004/b91f76e7/attachment.htm
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