Jim Dettman
jimdettman at earthlink.net
Fri Jun 4 07:41:24 CDT 2004
I've kept my mouth shut too even though I don't agree with all the things that have been stated<g>. Everyone misses the point that fundamentally, relational theory has nothing to do with computers per say. It deals with organizing the relations between pieces of data. Since computing systems store data, they fall under the theory, but the theory doesn't exist because of computers. It's a branch of mathematics in dealing with set relations. But we've gone through this several times. Anyone who's interested can look in the archives. And for the record, I'm not grouping myself with Joe Celko or Fabin Pascal. Suffice to say I fall somewhere in between the two camps in terms of living in the real world. There are times when using a surrogate makes sense and then there are others where it just adds complexity. Jim Dettman President, Online Computer Services of WNY, Inc. (315) 699-3443 jimdettman at earthlink.net -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com]On Behalf Of Arthur Fuller Sent: Thursday, June 03, 2004 9:50 PM To: 'Access Developers discussion and problem solving' Subject: RE: [AccessD] OT: The Great Primary Debate It's actually more complicated than that, and while I fall on the side of ANPKs, I do respect the opinions of such luminaries as Joe Celko, who despises ANPKs. His reason? They model nothing in the real world; his premise -- any data model that artificially maps real-world entitities is by defnition flawed. He works in different environments than I. Typically I think of the egg-carton, and question the significance of which two eggs I choose to make my morning omelet. He thinks in terms of "this alternator was manufactured by XYZ for use in Ford models T, U and V. It was manufactured on a day in a factory and signed off by employee ABC as valid and working. Or to put his argument another way, I am a vendor of antiques and I have precisely one Queen Anne male chair (the difference between male and female being the armrests or lack thereof), which was hand-crafted by Hortense Witherspoon circa 18whatever. If I read him correctly (which, given my rapidly increasing senior moments, may be a faulty assumption), these cases (as opposed to the eggs in a carton) can all be given primary keys which derive from the data themselves, and do not falsify the picture by introducing an ANPK. I don't mean to resurrect the PK debate, nor to say that I agree with Joe. Concerning the latter, I emphatically do not agree. But he is a luminary that has written some brilliant books and probably makes twice the money that any three of us on this list do. Oracle and DB/2 seem to be his favorite turf, but I could be wrong about that part. Anyway, I stand clearly on the side of ANPKs and have found none of Joe's arguments on this subject persuasive. But as he wrote to me in an email a while back, "Go take a data-modeling course." Well, I took his advice and took a data-modeling course, and I remain unpersuaded. Arthur -----Original Message----- From: accessd-bounces at databaseadvisors.com [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Mitsules, Mark S. (Newport News) Sent: Wednesday, June 02, 2004 9:07 AM To: 'Access Developers discussion and problem solving' Subject: RE: [AccessD] OT: The Great Primary Debate As a potential hypothesis, I would have to agree. But in order to prove your hypothesis you should have presented the opposite "Fear Factor" as well:) That those in favor of AutoNumbers fear the user's ability to screw up even a five-field compound key by unwittingly uncovering the one situation in which it would fail;) And, that those in favor of AutoNumbers fear the complexity and never-ending maintenance that will "inevitably" result from such a decision;) Mark -----Original Message----- From: Lawhon, Alan C Contractor/Morgan Research [mailto:alan.lawhon at us.army.mil] Sent: Wednesday, June 02, 2004 8:51 AM To: 'Access Developers discussion and problem solving' Subject: RE: [AccessD] OT: The Great Primary Debate Martin, Susan, John, Jim, Charlotte, Drew, Gustav, et al: I think there is another factor involved in this "AutoNumber versus Natural Key" PK debate. For lack of a better word or terminology, I'm going to refer to it as the "Fear Factor" or a fuzzy type of generalized apprehension. This "apprehension" boils down to something along the lines of, "Well, what happens if the AutoNumber field gets corrupted or somehow those autonumbers get jumbled or out-of-sequence? If that happens, then how do we re-establish the primary keys and make sure they're associated with the correct records?" (The more records there are in a table, the more heightened this fear or apprehension tends to be.) The answer to this [unspoken] question is that they would rather avoid the possibility altogether by using non-Autonumber composite (i.e. "Natural") primary keys. It appears, from my experience, that folks who have not been trained in database theory seem to have an intuitive preference for natural keys - even when such "natural" keys involve the concatenation of two (or more!) fields - with all the headaches that come from trying to manage such an unweildy arrangement. I have experienced this issue firsthand here at work. We are managing a substantial (several million record) environmental database with multiple linked tables, numerous views, action queries, macros, et cetera ... This application requires primary and foreign keys in nearly all of the base tables. Early on we tried to persuade the senior project engineer, (a chemical engineer by profession), of the wisdom of using single-field AutoNumbers for the PK in the most important table of the application. He adamantly refused, insisting on a two-field composite primary key. We did our best to try and persuade him that an autonumber PK was best, but he wouldn't hear it. Since this engineer has major input into our performance appraisals, the programming staff acquiesced. We decided to live with a "composite" PK - even if we didn't like it or agree with it. After giving this a great deal of thought, I have come to the conclusion that folks who prefer "natural" (composite) PKs do so due to a general apprehension or mistrust of AutoNumbers. I don't think it is a "technical" issue, but rather a "people issue" centering around fear and apprehension. Whenever one sees a strong visceral reaction, (such as what Martin saw yesterday), this tends to reinforce my perception that this is more of a "people problem" than a purely "technical" problem. Does this make any sense to the rest of you? Alan C. Lawhon -----Original Message----- From: Martin Reid [mailto:mwp.reid at qub.ac.uk] Sent: Tuesday, June 01, 2004 1:17 PM To: Access Developers discussion and problem solving Subject: [AccessD] OT: The Great Primary Debate I was taking day one of a 4 day Programming SQL Server 2000 course today. 8 Oracle programmers moving to SQL Server, 6 of our Ingres programmers moving to SQL Server. Came to the section on Table Design. I said use an Identity value for the PK on the table - all h%ll brooke loose for the next hour as the great debate happened live in person. Pity JC wasnt there to back me up (<: Was split between the younger developers who supported the use of the ID column and the older developers and DBAs who use natural keys. Almost a 50//50 split on age lines maybe reflecting different attitutes to design. Took me about 20mins with one of the older guys to explain how the relationship was maintained using Idt IDs as opposed to his staff number. He seemed to have real problems getting the concept. Martin -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com -- _______________________________________________ AccessD mailing list AccessD at databaseadvisors.com http://databaseadvisors.com/mailman/listinfo/accessd Website: http://www.databaseadvisors.com