Re: unique constraint interpretation.

Just re-read the relevant clause in the spec a few times and came to the 
conclusion that Xerces indeed has a bug. That is, the quoted conclusion is 
not correct, and the testcase attached to 18405 should be valid.

Thanks,
Sandy Gao
XML Parser Development, IBM Canada
(1-905) 413-3255
sandygao@ca.ibm.com




"Tishkin, Eugene" <etishkin@mackenziefinancial.com> 
Sent by: xmlschema-dev-request@w3.org
11/09/2005 09:31 AM

To
<xmlschema-dev@w3.org>
cc

Subject
unique constraint interpretation.






Hi,
 
The below is the comment from Xerces parser BUG 18405 report:
================================================ 
"3 For each node in the
·target node set·
all of the
{fields},
with that node as the context node, evaluate to either an empty node-set 
or a 
node-set with exactly one member, which must have a simple type."

The target node set is the set of nodes on which the selector is matched. 
Note 
that this condition must hold for *any* identity constraint; only in 
bullet 4 
of the tableau are the differences between key and unique described. 
Therefore, it seems clear that, if a selector matches, then either all of 
the 
fields must match or none of them must match; even for xsd:unique, you 
can't 
have some fields matching.
=========================================================
 
Especially I'm interested in the conclusion:
 
"Therefore, it seems clear that, if a selector matches, then either all of 
the 
fields must match or none of them must match; even for xsd:unique, you 
can't 
have some fields matching."
 
Is this a correct interpretation of unique constraint? 
 
Regards,
Eugene
 


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