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Anne Thomas Manes wrote:
>> Either the XML is persistent or it is transient. If the XML is persistent,
then the application works directly on the XML. If the XML is transient, then
the XML is transformed into some other format (language objects, relational
database, etc.) that the application works with.
There are hybrid situations when the XML is persistent in its native format and
it's also mapped to columns in databases.
Disk space is cheap these days so it doesn't cost much to do both of these:
1. Shred (decompose) a document. Map it into tables and index accordingly to
provide performance or support rich queries (e.g., geospatial data, maps,
images, time series, audio).
2. Store the original document in a column. Even when your primary queries
execute over tables created by decomposing a document, you may need to retrieve
the original document from time to time (e.g., resolve a billing dispute using
an audit trail of an e-business document exchange).
Developers have been using CLOB, VARCHAR and other SQL column types for storing
complete documents. The SQL:2003 standard added a new column type for XML, which
Oracle and Microsoft have implemented.
======== Ken North ===========
www.WebServicesSummit.com
www.SQLSummit.com
www.GridSummit.com
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