Here is Tom Lane's comment.
> Tomas Cerha <t.cerha@sh.cvut.cz> writes:
> > Aplying the NOT operator with << INET operator results always in false.
>
> > accounting=> SELECT * FROM a;
> > ip
> > --------
> > 10.1.1.1
> > 10.1.1.2
> > 10.2.1.2
> > 10.2.1.1
> > (4 rows)
>
> > accounting=> SELECT * FROM a WHERE ip<<'10.1/16';
> > ip
> > --------
> > 10.1.1.1
> > 10.1.1.2
> > (2 rows)
>
> > accounting=> SELECT * FROM a WHERE NOT ip<<'10.1/16';
> > ip
> > --
> > (0 rows)
>
> What's going on here is that the optimizer is simplifying "NOT x<<y"
> (network_sub) into "x>>=y" (network_supeq), because the pg_operator
> entry for << claims that >>= is its negator. This example demonstrates
> that that ain't so.
>
> Can anyone comment on whether any of the inet operators are actually the
> correct negator of << ? For that matter, are inet's other commutator
> and negator declarations just as broken?
>
> regards, tom lane
>
> ************
>
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