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"Programmers can't get IPv6 thus that is why they do not have IPv6 in their applications"....



On 11/30/2012 09:45 AM, Ray Soucy wrote:
> I'll see your disagree and raise you another ;-)
>
> I would say you almost never want to store addresses as character data
> unless the only thing you're using them for is logging (even then it's
> questionable).  I run into people who do this all the time and it's a
> nightmare.
>
> It's easy to store a v6 address as a string, but when you want to select a
> range of IPv6 addresses from a database, not having them represented as
> integers means you can't do efficient numerical comparisons in your SQL
> statements, it also makes indexing your table slower; to put it simply, it
> doesn't scale well.
>
> So as a general rule, if you need to do any comparison or calculation on a
> v6 address, please don't store it as a string.
>
> >From an efficiency standpoint, you want to store it in chunks of the
> largest integer your DBMS supports.  If a DBMS supports 128-bit integers
> and has optimized operations for them, then go for it.  Most only support
> 64-, or even 32-bit.  I say 64-bit because that's what the majority of
> current systems actually support and I don't see anyone coming out with a
> 128-bit architecture ;(
>
> For convenience I would very much love to see MySQL include inet6_aton and
> inet6_ntoa, along with a 128-bit data structure that would
> be implemented as either a pair of 64-bit or 4x 32-bit values depending on
> the architecture.  But from a performance standpoint, I really don't want
> my DBMS doing that calculation; I want the application server doing it
> (because it's much easier to scale and distribute the application side than
> the storage side).
Postgresql has an inet data type that handles both ipv4 and ipv6 addresses with a slew of
functions to manipulate the data type.

http://www.postgresql.org/docs/8.4/static/functions-net.html

> Note that I'm talking about more from a database storage perspective than
> an internal application perspective.
>
> By all means, you should use the standard data structure for v6.  As
> mentioned below a lot of the internal structures use 8-bit unsigned
> integers (or char); but that's mainly a hold-over from when we had the
> reality of 8-bit and 16-bit platforms (for compatibility).  With unions,
> these structs are treated as a collection of 8, 16, 32, 64 or a single
> 128-bit variable which makes it something the developer doesn't need to
> worry about once the libraries are written.
>
>
>
>
> On Thu, Nov 29, 2012 at 9:55 AM, William Herrin <bill at herrin.us> wrote:
>
>> On Thu, Nov 29, 2012 at 9:01 AM, Ray Soucy <rps at maine.edu> wrote:
>>> You should store IPv6 as a pair of 64-bit integers.  While PHP lacks
>>> the function set to do this on its own, it's not very difficult to do.
>> Hi Ray,
>>
>> I have to disagree. In your SQL database you should store addresses as
>> a fixed length character string containing a zero-padded hexadecimal
>> representation of the IPv4 or IPv6 address with A through F forced to
>> the consistent case of your choice. Expand :: and optionally strip the
>> colons entirely. If you want to store a block of addresses, store it
>> as two character strings: start and end of the range.
>>
>> Bytes are cheap and query simplicity is important. Multi-element
>> indexes are messy and the code to manage an array of integers is
>> messier than managing a character string in most programming
>> languages. memcmp() that integer array for less or greater than? Not
>> on a little endian machine!
>>
>>
>>> Here are a set of functions I wrote a while back to do just that
>>> (though I admit I should spend some time to try and make it more
>>> elegant and I'm not sure it's completely up to date compared to my
>>> local copy ... I would love some eyes on it to make some
>>> improvements).
>>>
>>> http://soucy.org/project/inet6/
>> If we're plugging our code, give my public domain libeasyv6 a try. It
>> eases entry into dual stack programming for anyone used to doing
>> gethostbyname followed by a blocking connect(). Just do a
>> connectbyname() with the hostname or textual IP address, the port, a
>> timeout and null options. The library takes care of finding a working
>> IPv4 or IPv6 address for the host and connecting to it in a timely
>> manner.
>>
>> http://bill.herrin.us/freebies/
>>
>> Currently Linux only but if you're willing to lose timeout control on
>> the DNS lookup you can replace getaddrinfo_a() with standard
>> getaddrinfo() and the code should run anywhere.
>>
>> Regards,
>> Bill Herrin
>>
>>
>> --
>> William D. Herrin ................ herrin at dirtside.com  bill at herrin.us
>> 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/>
>> Falls Church, VA 22042-3004
>>
>
>


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