On Apr 29, 2005, at 2:37 PM, mmalcolm crawford wrote:
For example, if a Person entity should have a 'photo' attribute,
then create a Photo entity with just a single attribute -- the
data -- and if you care a relationship back to the Person
(typically modeling relationships in both directions is a Good
Thing). Then create a relationship from the Person to the Photo
entity. This will mean that photo data is only loaded from the
persistent store if you actually use it.
Is this true in general (or at least for SQLite stores)?
Relationships are loaded on demand, but attributes are loaded when
the object is? Is there any situation where attributes will be
lazily loaded, or is the concept of faulting only for entities? I'm
thinking of an example of an object that has
ObjectEntity
name
date
comments
It is being displayed in a table view, but the table view only has
columns for name and date, for example.
Faulting only applies to relationships (so in your example comments
will be loaded along with the other attributes on fetch), and is only
really relevant if you use a SQLite store since it can fetch data on
an as-needed basis. The other stores -- XML and binary -- both load
the whole persistent store into memory when they're accessed.
mmalc
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