On 06/08/10 21:55, Peter Eisentraut wrote:
On fre, 2010-08-06 at 14:43 +0100, Mike Fowler wrote:
Or perhaps it could return a string instead of a boolean: content,
document, or NULL if it's neither.
I like the sound of that. In fact this helps workaround the IS
DOCUMENT
and IS CONTENT limitations such that you can you can select only
content, only documents or both is you use IS NOT NULL.
Unless anyone sees a reason that this function needs to remain a
boolean function, I'll rework the patch over the weekend.
What is the actual use case for this function? Is the above behavior
actually useful?
The idea is to be able to filter a table that contains XML in TEXT that
might not be well formed. Knowing that you're only dealing with well
formed XML prevents you blowing up when you attempt the cast.
One reason to stick with boolean is backward compatibility.
To be honest I'm happiest with returning a boolean, even if there is
some confusion over content only being valid. Though changing the return
value to DOCUMENT/CONTENT/NULL makes things a touch more explicit, the
same results can be achieved by simply running:
SELECT data::xml FROM mixed WHERE xml_is_well_formed(data) AND data::xml
IS DOCUMENT;
Regards,
--
Mike Fowler
Registered Linux user: 379787
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