INET operators and NOT

Your name               :       Tomas Cerha
Your email address      :       t.cerha@sh.cvut.cz

System Configuration
---------------------
  Architecture (example: Intel Pentium)         : Intel Pentium MMX

  Operating System (example: Linux 2.0.26 ELF)  : Linux 2.2.5-15 ELF

  PostgreSQL version (example: PostgreSQL-6.5.3): PostgreSQL-6.5.3

  Compiler used (example:  gcc 2.8.0)           : installed from RPMs

    installed packages:
        postgresql-6.5.3-1.i386.rpm
        postgresql-perl-6.5.3-1.i386.rpm
        postgresql-server-6.5.3-1.i386.rpm
        postgresql-tcl-6.5.3-1.i386.rpm
        postgresql-test-6.5.3-1.rpm
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Please enter a FULL description of your problem:
------------------------------------------------

Aplying the NOT operator with << INET operator results always in false.
See the example below:

This is the contents of table a:

accounting=> SELECT * FROM a;
      ip
--------
10.1.1.1
10.1.1.2
10.2.1.2
10.2.1.1
(4 rows)

Now, let's select only those hosts from subnet '10.1/16': (works fine)

accounting=> SELECT * FROM a WHERE ip<<'10.1/16';
      ip
--------
10.1.1.1
10.1.1.2
(2 rows)

And now, I only apply NOT to prewious statement ....

accounting=> SELECT * FROM a WHERE NOT ip<<'10.1/16';
ip
--
(0 rows)


But that is not true! I tryed this also with other versions of postgress
on other machines and the result was always the same. But this makes all
about INET operators quite unusable, when I am not able to exclude some
address space (I can only include them). Or is there another way to do
It?



Please describe a way to repeat the problem.   Please try to provide a
concise reproducible example, if at all possible:
----------------------------------------------------------------------

CREATE TABLE a (ip inet);

INSERT INTO a VALUES ('10.1.1.1');
INSERT INTO a VALUES ('10.1.1.2');
INSERT INTO a VALUES ('10.2.1.2');
INSERT INTO a VALUES ('10.2.1.1');

SELECT * FROM a;
SELECT * FROM a WHERE ip<<'10.1/16';
SELECT * FROM a WHERE NOT ip<<'10.1/16';

DROP TABLE a;

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Thank you for any idea which could help me with this problem ...

Tom Cerha, student, FEE CTU Prague Czech Republic