On 2/9/2012 4:10 PM, David Salisbury wrote:
On 2/9/12 10:08 AM, Rich Shepard wrote:
I have reports containing macroinvertebrate collection data for several
hundred (or several thousand) of taxa. There is no natural key since
there
are multiple rows for each site/date pair. Years ago Joe Celko taught
me to
seek natural keys whenever they might exist. They don't here. That's
why I
specifically mentioned that in my message.
Interesting. I used to think natural keys were okay, but have since decided
that surrogates are the way to go. That second layer of abstraction allows
for much easier data modifications when needed. What would be an example
of a natural key that would be good to use, and why would it be
preferable??
I'd think the key value must never change, and even say kingdom values in a
taxa table could possibly change.. might discover something new and do a
little reordering. :) Also natural keys might be strings, which I'm
thinking
would not be as efficient as integers for an index.
-ds
Yeah, this is a Vim vs Emacs war. (Vim, :-) )
I prefer surrogates like you. Its way to easy to pick something that
one day has to change.
Within the last year I remember a long thread about this same thing.
-Andy
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