GUID Factory

[David Merrill]

On Sun, Dec 17, 2000 at 08:49:02PM -0500, Jean-David Beyer wrote:
> Christopher Browne wrote (in part):
> > 
> > This is something that is indeed appropriately generated in the "engine,"
> > not in the DB; the relevance to the DB is to ask whether it can use the
> > GUID as one of its keys, and whether or not the DB supports foreign keys.
> 
> What is this "foreign key" stuff? I know what a "foreign key" is, and do
> not see how the concept applies here. If you want to stick a GUID into a
> record, tuple, or whatever you want to call it, you may do so, of
> course. If you search based (at least in part) on that field, column,
> attribute, or whatever you want to call it, often enough, it may be
> appropriate to make an index on that. Most relational DBMSs permit
> indexing any field (unless it is considered "large", perhaps, but I
> cannot imagine the GUID would be large). But that decision need not be
> made until you know enough about the retrieval requirements of the
> system to make that decision. One nice thing about using a rdbms is that
> such decisions can be deferred indefinately, and changed from time to
> time without changing the applications running against the database at
> all.
> 
> Whether you consider that field to be a foreign key or not depends on
> whether or not it is the primary key of another table, relation, or
> whatever you want to call it. Even then, you would not need to declare
> it to be a foreigh key unless you want to enforce the relationship
> between the two tables (which you probably should).
> 
> Or am I missing something?

Just that the primary place a GUID is used is as a primary key, and
foreign keys in those tables' child tables.

-- 
Dr. David C. Merrill                     http://www.lupercalia.net
Linux Documentation Project                dmerrill@lupercalia.net
Collection Editor & Coordinator            http://www.linuxdoc.org
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