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ORA-XQ-080-C: Enforcement of consistency constraints

From: Stephen Buxton <Stephen.Buxton@oracle.com>
Date: 16 Feb 04 11:38:14
Message-Id: <200402161938.i1GJcEb26577@rgmgw4.us.oracle.com>
To: public-qt-comments@w3.org

SECTION 2.2.5 : Consistency constraints

First para, last sentence: "Enforcement of these consistency 
constraints is beyond the scope of this specification."
I can think of three ways a violation could occur:
a) The XQuery language specification itself specifies a violation
of one of these constraints.  Of course, we are fallible and 
mistakes happen, but presumably the working group will endeavor
to fix any such inconsistencies when they are reported.
b) The initialization of the static and dynamic context provides an
inconsistent 'start state' for XQuery expression evaluation.  
This can be handled in either of two ways:
  i) by specifying that the XQuery implementation shall begin 
     by checking its static and dynamic context for violations
     and report any violations as exceptions.
  ii) that might be regarded as too much overhead, so you 
     might prefer to specify 'lazy' constraint checking, only
     checking a value when the value is referenced, or some 
     aspect of a value is referenced.
c) The violation occurs dynamically during expression evaluation.
This can be handled by specifying that the constraints shall
be checked whenever a value is constructed.

- Steve B.
Received on Monday, 16 February 2004 14:38:18 UTC

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