On 09/17/2015 07:51 AM, Tom Lane wrote:
Adrian Klaver <adrian.kla...@aklaver.com> writes:
On 09/17/2015 07:34 AM, Tom Lane wrote:
Ah, sorry, actually what IS [NOT] DISTINCT FROM looks up is the "="
operator.

So the docs should be changed?
As they stand now:
http://www.postgresql.org/docs/9.4/interactive/functions-comparison.html
"For non-null inputs, IS DISTINCT FROM is the same as the <> operator."

Well, it's an oversimplification to begin with.  Do we want to try to
cram all of these implementation details in there?

No, just that IS DISTINCT ON is dependent on '=' and will not work on data types that do not have that operator. That would also cover the IS NOT DISTINCT FROM case where '=' is the operator 'alias'.


                        regards, tom lane



--
Adrian Klaver
adrian.kla...@aklaver.com


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