Xpath difference between Oracle 10g and Oracle 11g

Question

All,
I'm working on moving our existing stored functions from Oracle 10g (10.2.0.4.0) to Oracle 11g (11.2.0.1.0) and so far, everything has worked just fine on Oracle 11g...execpt for one xpath statement.
The statement below works fine in Oracle 10g (10.2.0.4.0):
extractValue(inv_dtl_img, '/service//ground/sortKeyCode') AS "srt_key_cd",
Please note: I need to use the double slash "//" in order to ignore the two different elements in the schema.
However, in Oracle 11g (11.2.0.1.0), when this statement is executed in the stored function, I get this:
ERROR at line 1:
ORA-00932: inconsistent datatypes: expected - got -
The extractValue command is pulling data out of an XMLType column, and the corresponding XML schema looks like:
<service>
<trans>
<ground>
<sortKeyCode>
</sortKeyCode>
</ground>
</trans>
<nontrans>
<ground minOccurs=0>
<sortKeyCode>
</sortKeyCode>
</ground>
</nontrans>
</service>
Please note: In the XML message, the "trans" and "nontrans" elements are exclusive, so both will never be populated at the same time. A typical XML message would look like this:
<service><trans><ground><sortKeyCode>3</sortKeyCode></ground></trans></service>
or this:
<service><nontrans><ground><sortKeyCode>5</sortKeyCode></ground></nontrans></service>
In the schema, the sortKeyCode has been defined in both places as "string maxlen=3", so the datatype of that element is exactly the same in both the "trans" and "nontrans" sections of the schema. The only difference in the schema (outside of the trans and nontrans tags) is the fact that the second "ground" tag is defined with a "minOccurs=0". Could Oracle 11g be treating the schema differently than Oracle 10g, resulting in the error?
Any thoughts would be appreciated.

Answer 1

The only way to get an quick answer to that one is to file a service request with Oracle support. It could be a bug or a correct change regarding W3C behavior. Despite this, you moving to 11.2, the extract/extractvalue etc propriety Oracle solutions are deprecated from 11.2 and onwards. The more sensible way to move forward, although, I know more work intensive, is to apply the XQuery alternatives like xmlexist, xquery or xmltable functions.
Moving to EXTRACT is a bad idea, because this alway will be treated as an XML fragment. If you unlucky then Oracle will deal with this in memory via DOM (the standard solution regarding XML parsing if every smart thing within Oracle can not be applied) and this will result in a performance downgrade due to high CPU and Memory consumption/overhead...
Your pick...