Re: Best way to index IP data?

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Pomarede Nicolas <npomarede(at)corp(dot)free(dot)fr>
Cc: Andrew Sullivan <ajs(at)crankycanuck(dot)ca>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Best way to index IP data?
Date: 2008-01-12 00:51:19
Message-ID: 28998.1200099079@sss.pgh.pa.us
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Pomarede Nicolas <npomarede(at)corp(dot)free(dot)fr> writes:
> And it's true for IPv6 too, storing an IP that refer to an end point and
> not a subnet is requiring twice as much data as needed, because the
> netmask would always be ff:ff:ff:..:ff
> So, for people dealing with large database of IPs, it would be nice to be
> able to save 50% of the corresponding disk/cache/ram space for these IPs.

There seem to be a number of people in this thread laboring under the
illusion that we store a netmask as a mask. It's a bit count (think
/32 or /128) and occupies a whole one byte on disk. Killer overhead,
for sure.

regards, tom lane

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