Re: Am I supposed to be all scared of compound primary keys?

On Sat, 2010-05-01 at 19:25 -0700, Mike Christensen wrote:

-->I have a table that stores a user ID and a subscription type, and this is really all it needs to store and any pair of values will always be unique. In fact, I think this pair should be the primary key on the table. However, I'm using Castle ActiveRecord which says at:

http://www.castleproject.org/activerecord/documentation/v1rc1/usersguide/pks.html#CompositePK

And I quote:

Quick Note: Composite keys are highly discouraged. Use only when you have no other alternative.

I get the feeling they're discouraged from a SQL point of view, but it doesn't actually say why anywhere. Is there any good reason to avoid using composite keys on a table? Why waste the space of an extra key if you don't have to? Thanks!
-->
-->I'm not familiar with this project.. That said it seems they have some automated SQL updating/insert/relation building going on in the classes. Nothing more than simplifying the class initialising of .net ADO record sets which are overly complicated.
-->
-->It seems the class automation can not work with composite keys directly to build relation between classes; create SQL commands to up the records, and make sure within castle framework the composite key has been updated to all the other classes having relations.
-->
-->This warning has no impact on any database but a limitation and warning about Castle-project framework itself.
-->
-->The database does not care either way. Given this limitation is within the framework i follow the advice and not use a composite key. -->

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