Re: Efficiently searching for CIDRs containing an IP address

From: Alan McKay <alan(dot)mckay(at)gmail(dot)com>
To: "David F(dot) Skoll" <dfs(at)roaringpenguin(dot)com>
Cc: pgsql-admin(at)postgresql(dot)org
Subject: Re: Efficiently searching for CIDRs containing an IP address
Date: 2009-06-01 01:14:50
Message-ID: 844129e80905311814o4ab50ad8jb41172010ce612b4@mail.gmail.com
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Hmmm, I've never done this quite that way, but IPs - especially CIDRs
- are far easier to work with in binary format than in human-readable
format. At my old workplace about 5 years ago I wrote an IP
management system (PHP/MySQL) that stored the IP in binary and
human-readable formats, but all of the computations and comparisons
and other such stuff always took place with the binary values (binary
stored as a string of 0s and 1s as I recall).

So is this not simply easier to implement with a library of functions
to convert a string to binary and back? I recall in my implementation
I had only 4 or 5 functions including converting back-and-forth from
binary to human-readable, binary-AND, binary-OR and maybe one or two
others.

--
“Mother Nature doesn’t do bailouts.”
- Glenn Prickett

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