Date: Sat, 12 Jan 2008 01:00:48 -0500
From: "D'Arcy J.M. Cain" <darcy@druid.net>
To: Greg Smith <gsmith@gregsmith.com>
Cc: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: Best way to index IP data?
Message-Id: <20080112010048.27678be8.darcy@druid.net>
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On Fri, 11 Jan 2008 21:56:38 -0500 (EST)
Greg Smith <gsmith@gregsmith.com> wrote:
> On Fri, 11 Jan 2008, Steve Atkins wrote:
> 
> > You may well need netmasks to configure your interface, but there's 
> > absolutely no need for them to identify an IP endpoint, which is all you 
> > need to identify the destination the packet is going to, and that is the 
> > most common use of IP addresses.
> 
> Technically you can't ever send a packet unless you know both the endpoint 
> and your local netmask.  As the sender, you're obligated to determine if 
> the destination is on your local LAN (in which case you send it there) or 
> if it goes to the gateway.  That's similar to a routing decision, but it's 
> not quite--if you don't have to look in a routing table, it's not actually 
> part of routing.

Not sure what your point is here.  Sure, you need the netmask but not
of every IP address you send to, only for the IP/network that you are
on.  That's a grand total of one netmask per interface that you need to
know.  And you don't store it in your database.

-- 
D'Arcy J.M. Cain <darcy@druid.net>         |  Democracy is three wolves
http://www.druid.net/darcy/                |  and a sheep voting on
+1 416 425 1212     (DoD#0082)    (eNTP)   |  what's for dinner.