OID's vs Relational Keys?
From: jason.glumidge_at_gmail.com <Jason.Glumidge_at_gmail.com>
Date: 21 Dec 2005 06:49:19 -0800
Message-ID: <1135176559.700113.120710_at_f14g2000cwb.googlegroups.com>
I have been reading an article by C.J.Date - "Object Identifiers vs. Relational Keys" in Relational Database Writings 1994-1997, and while I'm not really an OODBM's fan, there are a few things in it that I've found confusing: location, wheres an OID is location independent. Date sees no worth in a distinction between identity and equality,
stating that it is a nonsense that "two objects that look the same to
the user (meaning the user has no way to tell them apart) might in fact
be distinct." going on to say that there is no use for "duplicates". My
first impression is that this seems to happen all the time in the real
world, where while we know full well two things are distinct but do not
currently possess the attribute that defines this difference. Or there
are two items which are identical in all their defining attriubtes but
are still unique (their location is different for instance, which we
can't continually record).
Date: 21 Dec 2005 06:49:19 -0800
Message-ID: <1135176559.700113.120710_at_f14g2000cwb.googlegroups.com>
I have been reading an article by C.J.Date - "Object Identifiers vs. Relational Keys" in Relational Database Writings 1994-1997, and while I'm not really an OODBM's fan, there are a few things in it that I've found confusing: location, wheres an OID is location independent.
Now we all employ surrogate keys to enforce this distinction, but this is a value we've just artificially constructed, not part of the real items uniqueness. While the mechanism is different (and I agree with Date on the logistical differences) this seems to just be giving the tuple an identifier, again to allow a distinction between identity and equality (two items in an RDBMS are equal if everything apart from their surrogate id is the same), that he originally objects to.
I'm finding it tough seeing the wood from the trees with different types of databases. Received on Wed Dec 21 2005 - 15:49:19 CET