Re: xpath processing brain dead

Simon Riggs wrote:
> On Sun, 2009-03-01 at 18:22 -0500, Andrew Dunstan wrote:
>
>
>> I think the XML type needs to conform to the SQL/XML spec. However, we
>> are trying to apply XPath, which has a different data model, to that
>> type - hence the impedance mismatch.
>>
>> I think that the best we can do (for 8.4, having fixed 8.3 as best we
>> can without adversely changing behaviour) is to throw the
>> responsibility
>> for ensuring that the XML passed to the function is an XML document
>> back on the programmer. Anything else, especially any mangling of the
>> XPath
>> expression, presents a very real danger of breaking on correct input.
>>
>
> Can we provide a single function to bridge the gap between fragment and
> document? It will be clearer to do this than to see various forms of
> appending/munging, even if that function is a simple wrapper around an
> append.
>
>

I have no objection to providing an *extra* function that explicitly
wraps non-documents and prefixes the xpath expression in that case, and
is documented to have limitations. But I don't think we can provide a
single function that always "does the right thing", especially when that
is so ill-defined in the case of fragments.

cheers

andrew