From: Bruce Momjian <pgman@candle.pha.pa.us>
To: Dan Langille <dan@langille.org>
Cc: pgsql-sql@postgresql.org
Subject: Re: inet versus text for ip addresses
Date: Sun, 20 Jul 2003 23:47:04 -0400 (EDT)
Message-ID: <200307210347.h6L3l4L23262@candle.pha.pa.us> (raw)
In-Reply-To: <3F05DEA4.5526.6F4CF1C5@localhost>
Dan Langille wrote:
> The PostgreSQL inet datatype stores an holds an IP host address, and
> optionally the identity of the subnet it is in, all in one field.
> This requires 12 bytes.
>
> Using my "random" data of approximately 8000 IP addresses collected
> during previous polls, I've found the average length of an IP address
> is 13.1 bytes. An integer requires 4 bytes.
>
> First question: Why not store an option to store just an IP address?
> That should require less than the 12 bytes for inet.
We store inet and cidr in similar structures, and they are of variable
length (4 byte overhead):
/*
* This is the internal storage format for IP addresses
* (both INET and CIDR datatypes):
*/
typedef struct
{
unsigned char family;
unsigned char bits;
unsigned char type;
union
{
unsigned int ipv4_addr; /* network byte order */
/* add IPV6 address type here */
} addr;
} inet_struct;
/*
* Both INET and CIDR addresses are represented within Postgres as varlena
* objects, ie, there is a varlena header (basically a length word) in front
* of the struct type depicted above.
*
* Although these types are variable-length, the maximum length
* is pretty short, so we make no provision for TOASTing them.
*/
typedef struct varlena inet;
In 7.4, we support IPv6, so they will be even larger.
--
Bruce Momjian | http://candle.pha.pa.us
pgman@candle.pha.pa.us | (610) 359-1001
+ If your life is a hard drive, | 13 Roberts Road
+ Christ can be your backup. | Newtown Square, Pennsylvania 19073
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: pgman@candle.pha.pa.us, dan@langille.org
Subject: Re: inet versus text for ip addresses
In-Reply-To: <200307210347.h6L3l4L23262@candle.pha.pa.us>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox