On 09/06/10 17:14, Tom Lane wrote:
> Robert Haas<robertmhaas@gmail.com> writes:
>
>> It's possible. I don't really see a reason not to add an = operator
>> for XML - does anyone else?
>>
> Yes, that was considered and rejected, IIRC. What is your definition
> of equality for xml?
>
Yes - but in that previous discussion the optimizer (lack of)
information was not considered (or known I suspect), so maybe a rethink
is worthwhile?
It seems that the nub of this issue is that there are conceptually two
types of =, one for datatype specific comparison, and one for optimizer
statistical information calculation. However the system allows only the
first, so if you don't (or can't) have one then you lose some possibly
important optimization data.
regards
Mark