[Tagging] football or soccer ?

Anthony osm at inbox.org
Thu Jul 1 14:25:44 BST 2010


On Thu, Jul 1, 2010 at 8:08 AM, John F. Eldredge <john at jfeldredge.com>wrote:

> In fact, the technique of having the user select from a list of words, but
> actually storing the value as an arbitrary ID (generally numeric), is the
> recommended technique in database design.  It is called "normalizing the
> database".
>

Umm...no.  At least, not exactly.  If a single column is independent from
other columns, it is not necessary for normalization to store it as an
arbitrary ID.  (For example, if you have a database table containing a
driver's license number, date of birth, and hair color, you generally
wouldn't store the hair color as an arbitrary ID and then have a separate
table to look up the hair color.  It certainly isn't necessary for
normalization.  Assuming driver's license number is your primary key, hair
color is a fact about the key, the whole key, and nothing but the key.)

If you're using a crappy "DBMS" you might do this anyway, not for
normalization, but for performance purposes, because the DBMS is too stupid
to do it automatically behind the scenes for you.  If you're using a good
DBMS, it won't be necessary, though.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/tagging/attachments/20100701/131bb6b9/attachment.html>


More information about the Tagging mailing list