Re: org.postgresql.util.PSQLException: ERROR: could not identify an equality operator for type xml

Kevin Grittner-5 wrote
> gajendra s v <

> svgajendra@

> > wrote:
>
>> I have added one column with xml type ,after adding I am getting
>> following error.
>>
>> org.postgresql.util.PSQLException: ERROR: could not identify an equality
>> operator for type xml
>
> The UNION operation requires comparing all columns in the result
> record to remove duplicates.  To identify duplicates, there must be
> a notion of equality defined (getting technical here) by a default
> btree opclass for the type.  XML does not have one, so UNION of a
> result set including an XML column is not allowed.
>
> Do you need the duplicate removal?  If not, use UNION ALL.  If you
> need that you may need to cast the XML to text for intermediate
> steps and then cast back to XML at the outermost level.

The other option is to only union the PK field(s) on KM_COURSE_MAST then as
a final outer query join that union-ed result back with KM_COURSE_MAST using
the PK and attach whatever additional columns your query desires.

David J.

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