DBAs are evil

A long time ago just down the road, no matter who asked you your name, you always gave the same reply.

" I am Connor MacLeod of the Clan MacLeod."

DBAs, who where good at the time, where stoked. FirstName, LastName and Clan..  Nice natural composite key.

As usual, we screwed it up, breed like rabbits and ended up doing Satan's work.  The answer now depend on who's asking...
To the telephone company I am  SUCKER093546
To the Government   I am  SLAVE8273 

And who is responsible for this? DBAs. They don't see people as normal people do, they are just nodes on a B-tree and the B-Tree damn well better be as compact as possible.

And so it came for my time in the devil's recruitment drive.  Should the identifier be an INT > 0 with the Identity property set or a GUID?

Identity GUID Weighting
Smallest Largest 10
Not Updateable Updateable 10
Fastest Slowest 10
Locally unique Globally Unique 50
Proprietary Open Implementation 10
Hardest maintenance Easiest maintenance 10

The highest weighting is given to the scope of the uniqueness for this application. It is really the ability of a client to create a valid key regardless of connectivity state.  This is core functionality so a no-brainer really.

If I can just get the person to have the GUID imbedded in his forehead in Code 39 symbology, I'll get good seats for Armageddon. :-)

Print | posted on Friday, October 08, 2004 12:54 PM


# Really a Key?

left by Brett at 10/9/2004 1:05 AM Gravatar

Does the Normal Form rules consider identity or GUID a key?

# re: DBA's are evil

left by Richard Tallent at 10/9/2004 5:35 PM Gravatar
Both an integer or a GUID ID can be candidate keys, but neither is a *natural* key. If anything, the integer is "more natural" because it has the real-world meaning of relative insert order, but that is hardly a meaningful attribute.

# re: DBA's are evil

left by DavidM at 10/11/2004 8:34 AM Gravatar

Technically Richard is right. The Normal Forms' assume that the key is the "right" key. It's a business decision for what the key and the non-key attributes mean in the enterprise.

I have been thinking of creating a "short" table for the person entity.. Say (GUID, FirstName, LastName, Contact).
GUID becomes the surrogate & primary key and {FirstName, LastName, Contact} becomes the natural key enforced by unique constraint.

Then maybe give the user the option to drop the unique constraint, with a stern warning of course.

# So what does that buy you?

left by Brett at 10/12/2004 1:27 AM Gravatar
You add the contraint, which adds an index. The GUID or IDENTITY would be used for...? RI? The old, "I can change the natural key with no impact to my relational data" argument? Or is it the saving space argument. How about faster access to the data (the one where the indexes are smaller and the joins are plentiful...still don't see how that's faster then going against 1 table).

# re: DBA's are evil

left by DavidM at 10/12/2004 8:10 AM Gravatar
The GUID will be the surrogate key Brett. Yes it will be for RI. You know me Brett, speed, number of joins and size are irrelevant to me during the logical design phase. Besides the ability of the client to create a valid key in a disconnected state, the other reason for not using the other candidate key in RI is far scarier/uglier...

Further down the RI chain is the mother of all "junction" tables. The SQL Server limit of 900 bytes for a key becomes a real issue.

I am hoping I can implement the composite key constraint but the fact that I have to "create" another key because of an implementation issue is
a sad fact of reality.

Seriously, any suggestions are welcome.

# re: DBA's are evil

left by T at 10/19/2004 1:03 PM Gravatar
two right
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