[Data-modeling] Adding a date/time CVT to organization members

[Robert Cook]

Jeff --

One solution here is to "mediate" all relationships, making them CVTs,  
which would give us this capability in the near term.  The problem  
with this, as you can see from the developer mailing list, is that  
CVTs confuse people trying to make a straightforward query, and many  
of those people don't care that there is additional information  
attached to the relationship.

The other solution is to provide lower-level support that allows two  
representations of the relationship -- one simple and one with all of  
the other metadata like start date and end date.  Unfortunately, we  
don't yet have that capability as it deeply complicates how we handle  
and optimize queries, so we're left to adding these date range CVTs in  
an ad-hoc way until we have the deeper capabilities.

R

On Feb 22, 2008, at 11:24 PM, Jeff Thompson wrote:

> Each time this comes up, it's my job to be the a**h*ole and ask the  
> converse question:
> Can you say what properties on any type you will *not* need to track  
> changing values over time...
>
> Jeff Prucher wrote:
>> We have had a request to insert a CVT between the types  
>> "organization" and
>> "organization member" in order to be able to track information  
>> about the
>> periods over which members have belonged to organizations. The CVT  
>> will
>> simply add start and end dates. (The properties that would be  
>> affected are
>> /organization/organization/members and
>> /organization/organization_member/member_of_these_organizations.)  
>> This is a
>> very straightforward fix to do, but doing so will break any  
>> applications
>> using these properties.  Is anybody using these properties, and if  
>> so, would
>> this be a problem for you?  We'd probably make the change in the  
>> middle of
>> March.
>>
>> Jeff Prucher
>> Type Librarian & Ontologist
>> Metaweb Technologies, Inc.
>>
>>
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>
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