Re: [PATCH] Add XMLEXISTS function from the SQL/XML standard

Peter Eisentraut wrote:
> On tis, 2010-05-25 at 15:31 +0100, Mike Fowler wrote:
>   
>> I've been reading the SQL/XML standard and discovered that it defines a 
>> function named XMLEXISTS that does exactly what the todo item 
>> xpath_exists defines. My original patch named the function as per the 
>> todo but I think using the function name from the standard is a better 
>> idea. So this patch is the same as before, but the function is now named 
>> XMLEXISTS instead of xpath_exists.
>>     
>
> The XMLEXISTS function works with XQuery expressions and doesn't have
> the call signature that your patch implements

Looking at the manuals of Oracle, Derby and DB2 I see how the call 
signature differs. I also note that Oracle's implementation is XPath 
only, Derby's is partial XQuery and DB2 appears to be full XQuery.

What do people prefer me to do? I see the options as:

1) Change the call signature to match the standard
2) Change the function name back to xpath_exists

Should option one be the more popular there's further choices:

1) Integrate XQuery support to completely match the standard, however 
this will require the addition of a new library libxquery
2) Leave the XPath as is, inline with Oracle's implementation
3) Hybrid approach. Since XML is a comple time option, add XQuery as 
another. Conditional completion gives the full XQuery support when 
available or just the XPath when not

Thoughts?

-- 
Mike Fowler
Registered Linux user: 379787