[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] RE: XML-enabled databases, XQuery APIs
Michael and Michael: Thanks. I've been wondering about overall performance of XML-enabled systems using non-traditional document types, eg, spatial data, and I had an XML expert with MS MVP status sleeping on my couch this weekend. 1) The effect of the binary is to increase the parser space. The relational system doesn't care because it uses an internal representation. However, the binary is reputed to create a faster parse. So while there is no query performance effect, isn't the shredder faster, that is, assuming XML on input? Wouldn't speeding up the pipeline be useful given 2)? 2) The effect of a document type varies by document type and the operation. Intuitively true for any XML document type. Since value handling depends on the value shape (the difference in working with unstructured text vs delimited text (the case for say long strings of vector values)), the relational model isn't the issue: microparsing is, and again, it might be better to be getting a binary back for some document types. The increase in parser space could be worth it if one handles a lot of documents of that type. It seems that if one were to enable SQL Server spatially, one would look for means to speed up that pipeline if the spatial data is coming in and out as XML. I have my doubts about articles that claim XML datatypes herald the end of middleware and about experts that tell me Microsoft is dumping XQuery for anything except SQL Server. Those seem to be opinions based on business document types, and not very large real-time maps or dynamic concept sets. len From: Michael Rys [mailto:mrys@m...] See below. Best regards Michael > From: Bullard, Claude L (Len) [mailto:len.bullard@i...] > What would be the consequences to XML datatypes in relational > databases should an XML binary standard be created? [Michael Rys] See my other response. > What is the efficiency or effectiveness of the indices and > queries given radically different kinds of XML document types > (eg, querying over a business document in XML vs a vector > graphic in XML)? Or put another way, how does the document > type as instanced in the XML datatype affect querying performance? [Michael Rys] Well, that depends heavily on the type of queries that you plan on running. The answer is about the same as if you would ask me about how efficient or effective the indices and the query optimizer is for different kinds of relational schemata (OLTP, OLAP, lots of tables with lots of columns etc.). It certainly does affect it, but the question at the moment should be more along the lines of: If your data fits the relational model and all you need is a relational processor, should you store the data as XML or should you shred it. And my answer today is: Just shred it.
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