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Re: Relation oddity
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Re: Relation oddity


  • Subject: Re: Relation oddity
  • From: Art Isbell <email@hidden>
  • Date: Mon, 26 Jun 2006 11:41:57 -1000

On Jun 25, 2006, at 10:32 PM, email@hidden wrote:

If you have a 'to many' relationship for which there may be 1,000,000 EO's in the fault then it is typically quite impractical to actually use this relationship because the poor system would need to load in 1,000,000 objects all the time! This is a typical scenario where a one-way relationship (the 'to-one') is a better idea.

Another case where a reverse relationship is bad news is when you have 'reference data' entities such as "ConsignmentType" for a "Consignment" EO. In such a situation, the "ConsignmentType" might be read-only, cache in memory and reside in the 'shared editing context'. One rule here is that you should not have a relationship going from entities that live in a regular editing context going into the shared editing context. So again, a non reflexive relationship is the way to go there as well.

I believe that a distinction needs to be made between no inverse relationship and an inverse relationship that's not marked as a class property. By making the to-many inverse relationship not a class property, EOF won't use it to keep the object graph consistent (i.e., it won't fetch those 1,000,000 objects), but I think EOF may still use this inverse relationship in ways that can be beneficial. So I always include inverse relationships in my eomodels but don't mark as class properties those to-many inverse relationships that might cause unacceptable fetching activity. Seems to work well for me.


Aloha,
Art

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