From: Daryl Richter <daryl@brandywine.com>
To: Michael Fuhr <mike@fuhr.org>
Cc: Axel Rau <Axel.Rau@Chaos1.DE>
Cc: pgsql-sql@postgresql.org
Subject: Re: Updating cidr column with network operator
Date: Tue, 27 Sep 2005 10:02:16 -0400
Message-ID: <433950E8.2050805@brandywine.com> (raw)
In-Reply-To: <20050926213309.GA37147@winnie.fuhr.org>
References: <ffaabb4676ab075beb4b6d041ec280c4@Chaos1.DE>
<4332C38E.5040807@brandywine.com>
<72c14f47f1dca0ae99e559cef56416a3@Chaos1.DE>
<43331359.1020703@brandywine.com>
<bbbf1059080c058d91cb869bf4cf750a@Chaos1.DE>
<20050923173204.GA80995@winnie.fuhr.org>
<4a95b442a12d5b4f3cc508868a13aba5@Chaos1.DE>
<20050926000541.GA11071@winnie.fuhr.org>
<f10bbbc30411862e1691fc7a905a8e5e@Chaos1.DE>
<20050926213309.GA37147@winnie.fuhr.org>
Michael Fuhr wrote:
> On Mon, Sep 26, 2005 at 12:34:59PM +0200, Axel Rau wrote:
>
>>Am 26.09.2005 um 02:05 schrieb Michael Fuhr:
>>
>>>On Fri, Sep 23, 2005 at 09:19:25PM +0200, Axel Rau wrote:
>>>
>>>>I'm sure this would be the cleanest solution but remember networks
>>>>change.
>>>
>>>Yes, which is why it's a good idea to automatically propogate those
>>>changes to tables that maintain redundant data.
>>
>>I would not call it redundant but normalized, because network has some
>>attributes, common to all addresses in the net, 1st of all the netmask.
>
>
> An attribute is redundant if it repeats a fact that can be learned
> without it. If one table contains IP addresses and another contains
> networks, then you can associate IP addresses and networks with a
> join of the two tables; indeed, this is how the "fix the network
> column" update works. Having a network column in the address table
> simply repeats what could be learned through the join.
>
>
I agree with Michael here. I think the fundamental problem with your
schema is that it is possible to have contradictory data between the
network and address table, always a bad situation.
I would replace network.id with a serial type value and make the cidr a
separate column, for example:
CREATE TABLE network (
id int not null PRIMARY KEY,
address cidr not null,
attr1 varchar(10) null
);
CREATE TABLE address (
id inet PRIMARY KEY,
network int NOT NULL
REFERENCES network
);
insert into network( id, address, attr1 ) values( 1, '10.1', 'a' );
insert into network( id, address, attr1 ) values( 2, '10.2', 'b' );
go
insert into address( id, network ) values( '10.1.0.1', 1 );
insert into address( id, network ) values( '10.1.0.2', 1 );
insert into address( id, network ) values( '10.1.0.3', 1 );
-- OOPS!
insert into address( id, network ) values( '10.2.0.4', 1 );
go
-- This will "correct" the any addresses put in the wrong network
update address
set network = ( select id from network where address >> address.id )
[additional network stuff snipped]
--
Daryl
"We want great men who, when fortune frowns, will not be discouraged."
-- Colonel Henry Knox, 1776
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To: pgsql-sql@postgresql.org
Cc: daryl@brandywine.com, mike@fuhr.org, Axel.Rau@Chaos1.DE
Subject: Re: Updating cidr column with network operator
In-Reply-To: <433950E8.2050805@brandywine.com>
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