Re: datatype advice numeric vs. varchar

On Jan 18, 2007, at 15:15 , Gene wrote:

> My calculations for disk space based off some information i found
> online are ( 8 + ( 2 bytes for every four digits) ) for numeric and (
> 4 + number of chars ) for a utf8 varchar datatype. Are these
> calculations still valid and has anyone tried using numeric for this
> purpose or is this really stupid?

While telephone numbers typically consist of digits, they're not  
numbers: they're strings of digits. For example, a telephone number  
in Tokyo is (typically) a string of 10 digits, beginning with "03".  
0311111111 as numeric would have unexpected results when retrieved.  
While you may not be concerned with Japanese phone numbers, I use it  
as an example to show that telephone "numbers" are actually strings.

In short, use strings (text/varchar).

Michael Glaesemann
grzm seespotcode net

PS. The number of bytes used to represent characters in UTF-8 varies.  
I believe digits (0-9) are all 1 byte/char.