Re: IP regex

Vladimir V. Kolpakov wrote:

> On Sun, Oct 31, 2004 at 11:31:33PM -0500, Jamie McCarthy wrote:
> 
>>[email protected] (Vladimir V. Kolpakov) writes:
>>
>>>On Sun, Oct 31, 2004 at 02:02:26PM -0500, Michael Stassen wrote:
>>>
>>>>Then you store an IP using INET_ATON(IP) and retrieve it with
>>>>INET_NTOA(ip_column).  That takes 4 bytes instead of 8 to 16
>>>
>>>It's very common mistake, -- to think integer occupies in
>>>databases 4 bytes. Please look DESC on your table, and you can
>>>find it takes 11 bytes, because is stored in character form.
>>
>>You misunderstand the output of DESCRIBE.  INT is stored in 4 bytes.
>>The "(11)" is the display width, which doesn't really affect anything
>>done through the perl interface.
> 
> 
> It's true,... but only for field data either, -- unless index is not created.
> 
> 
> --w

I don't understand.  Are you saying that an INT column will be more than 4 
bytes if you take its index into account?  Well, yes, but the same will be 
true for an indexed VARCHAR(15).  Furthermore, an index on a VARCHAR(15) 
will be larger than an index on an INT.  Try it.  You'll see that an index 
on an INT column has key_len=5, and an index on a VARCHAR(15) has 
key_len=16.  Together, a VARCHAR(15) column + index is at least twice the 
size of an INT column + index.

Michael


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