Michael, you're right, and I do now understand that an efficient serialization / deserialization of a matrix structure could be more straightforward using JSON than XML. However, without considering this potential overhead due to serializing / deserializing procedure, that should be or order "epsilon" comparing to linear algebra algorithms complexity, once loaded into memory, I don't think that a XQUERY coded matrix algorithm will be more efficient using XML or JSON as serialization choice.
Am I right ? 2014-02-02 Michael Kay <[email protected]>: > > On 2 Feb 2014, at 20:33, jean-marc Mercier <[email protected]> > wrote: > > > N-dimensional representation of arrays are quite straightforward with > XML too. Is there any incentive to expect better performances with a JSON > matrix representation rather than an XML one ? > > > > I think that if you had an XML schema for an XML representation of > N-dimensional arrays, and if the XPath processor recognized that schema and > used a custom tree representation for its instances, then arrays could be > represented using XML just as efficiently as using JSONiq arrays. But if > you use a general tree representation that allow any element names, > namespaces, base URIs, mixed content, attributes, and all the other > paraphernalia of XML, then it is likely to be significantly less efficient. > > For example: > > * XML is text-oriented, and using XML for numeric values invariably > involves string-to-number conversion, which is expensive > > * Numeric subscripts when addressing XML (as in para[3]) are likely to > have O(n) performance rather than constant performance, because the tree > structure is likely to be optimized for scanning all the children rather > than locating an individual child by its index. > > Michael Kay > Saxonica > >
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