19 October 2007

IP Addresses: No more char(15)'s allowed!

OK... This is my second entry on this blog. And it is about something I want every mysql/php newbie to know at the starting gate:

DON'T USE CHAR(15) FOR IP Address fields in mysql!

Well... what about the periods in ip addresses, you say?

Well... mysql has a FANTASTIC way of solving this issue! Convert the standard ip address into an unsigned integer!

ok... at first it sounds a little cryptic, but say it at least 3 times before your morning coffee:


loosely meaning....

INET_ATON = Internet address to number
INET_NTOA = Internet number to address

SO... try this:

mysql> SELECT INET_ATON('');
| INET_ATON('') |
| 3232235781 |
1 row in set (0.04 sec)

Now, let's reverse it!

mysql> SELECT INET_NTOA(3232235781);
| INET_NTOA(3232235781) |
| |
1 row in set (0.01 sec)

Fun, eh?

Now... what are the savings on this, you ask?

On a 17 million row table consisting only of an auto_increment id (another must; don't leave home without an auto_increment id!!), non-indexed exact searches are about the same. In fact, the searches on the char column sometimes perform up to 10% faster.

After indexing, exact searches are once again the same, although they take a fraction of the time they did when they were not indexed. However, where the crown jewel shines is on ranges. On a count of an ip range, on the int based table, the cost was 3.78 seconds, but on the char(15) based table, the cost was 26.21 seconds.

Also -- the size of the int based data table (MyISAM) is 148M compared to 329M on the char(15) based table.

Are you convinced now? :) If so, now you know what you're going to do!

Until next time (whenever that will be),

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