Forum OpenACS Q&A: Re: content_type__create_type for both item and revision table?

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3: Re: content_type__create_type for both item and revision table? (response to 1)
Posted by Dave Bauer on 06/09/04 10:15 PM
Ola is correct.

The most straightforward way to extend a content type is to subtype cr_revision. The additional complexity of extending the cr_item is not worth the storage savings or having some non-versioned extedned attributes in most cases.

So the simple solution is to store all of your type specific attributes in the subtype of content revision.

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5: Re: content_type__create_type for both item and revision table? (response to 3)
Posted by James Thornton on 06/09/04 11:13 PM
If you store all attributes as a content_revision, how do you specify unique constraints?
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7: Re: content_type__create_type for both item and revision table? (response to 5)
Posted by Jeff Davis on 06/09/04 11:41 PM
James, funny you should mention it...we were talking about it just today on irc.

You could enforce uniqueness in a revision table with a partial index.

You can do something similiar with a functional index on oracle (there is an example in chapter 7 in Tom Kyte's Effective Oracle by Design titled selective uniqueness).