Storage of Unstructured XML Documents ("Authored XML")

If the incoming XML documents do not conform to one particular structure, then it might be better to store such documents in CLOBs. For instance, in an XML messaging environment, each XML message in a queue might be of a different structure.

Oracle8i provides interMedia Text for indexing CLOB columns. This uses the extensibility mechanism to implement operators such as CONTAINS to search the text data. This has been extended to support searching of XML documents, including section and subsection searches.

interMedia Text Example: Searching Text and XML Data Using CONTAINS

This interMedia Text example presume you have already created the appropriate index.

SELECT * 
FROM   purchaseXMLTab 
WHERE  CONTAINS(po_xml,"street WITHIN addr") >= 1;

See Also: Chapter 5, "Using interMedia Text to Search and Retrieve Data from XML Documents" for more information on interMedia Text.

XML Document Unstructured Storage ("Authored XML"): Advantages

A CLOB storage is ideal if the structure of the XML document is unknown, arbitrary, or dynamic.

XML Document Unstructured Storage ("Authored XML"): Disadvantages

Much of the SQL functionality on object-relational columns cannot be exploited. Concurrency of certain operations such as updates may be reduced. However, the exact copy of the document is retained.