-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 11/27/06 23:58, Harald Armin Massa wrote: > Ron, > >> >> > In the "real world" there is no such thing as a primary key. At least >> not >> > over time. Not enough people understand the concept of a primary key to >> > make those things existent in the real world. >> >> There are lots of numbers. Credit card numbers, account numbers >> sales ticket numbers, etc, etc ad nauseum. Julian day and Julian >> date, even. You can't have lived in "the west" in the past 30 years >> without being surrounded by them. > > > Yes. There are a lot of numbers, but I the concept of a "primary key" is > totally different from the concept of "number". > > a "Primary Key" is supposed to identify <something< across time and space. > > Some time people thought that an IP-Number will do this... soonly after > there was NAT. > > Again, somebody thougt, "every microsecond is unique", and then there was > daylight saving. Until we get to velocities near c, every microsecond (ticks in OpenVMS are 100ns intervals, 0.1us, but that's just getting picky) *is* unique. But since DST is a valid concern, that's why you don't store the string 'YYYY-AA-DD HH:MM:SS.mmmm', you store a bigint with the ticks since epoch, and let the app interpret into environment-appropriate form. > Who gives guarantees that credit card numbers will not get reused after > years of inactivity? > > Yes, there are natural keys, and it's good to use them to identify things > for humans. But I got bitten many times by using them as primary. Many > things that "will not change, ever", just were changed on the next meeting. - -- Ron Johnson, Jr. Jefferson LA USA Is "common sense" really valid? For example, it is "common sense" to white-power racists that whites are superior to blacks, and that those with brown skins are mud people. However, that "common sense" is obviously wrong. -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQFFa+QjS9HxQb37XmcRAv6OAJ42fE2FSdhCdaySH1GUczpJlP1B1gCg1TpE OLTs3bhPVqT4YaFaNvMEbI0= =ktpr -----END PGP SIGNATURE-----
