| 摘要 |
The present invention concerns an XML data base management system (XDBMS, 10) for an XML database (20) comprising XML documents (30), each XML document (30) comprising one or more structural elements (35) and adhering to an XML schema (40), wherein at least one of the structural elements (35) is protected against access of a user (60), the XDBMS (10) comprising: a. an optimizer (300) adapted to process an XQuery (50) of the user (60) comprising one or more XQuery expressions (55) and further adapted to generate an optimized XQuery execution plan (70); b. an execution engine (400) adapted to execute the optimized XQuery execution plan (70) to retrieve XML data (80) from the XML database (20), characterized in that c. the optimizer (300) is adapted to generate the optimized XQuery execution plan (70), so that all XQuery expressions (55) relating to one or more of the structural elements (35) which are protected against access of the user (60) are ignored by the optimizer (300).
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