Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
- Subject: Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.)
- From: Scott Ellsworth <email@hidden>
- Date: Fri, 29 Apr 2005 14:32:29 -0700
On Apr 29, 2005, at 2:16 PM, mmalcolm crawford wrote:
On Apr 29, 2005, at 1:41 PM, Jim Correia wrote:
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.
Watch out for many-many relationships. They can be a true
performance killer.
Is this true in general (or at least for SQLite stores)?
Relationships are loaded on demand, but attributes are loaded when
the object is?
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.
What about fetched properties? The docs imply a lazy fetch, but I
have not had a chance to test.
On the other hand, I am not sure I grok when I would use a fetched
property, as opposed to a stored fetch request. Is there an implicit
"must be in a relatioship with the entity that the fetched property
is a part of" condition on a fetched property, or some such?
Scott
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| References: | |
| | >Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: Marc Blatt <email@hidden>) |
| | >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: mmalcolm crawford <email@hidden>) |
| | >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: Jim Correia <email@hidden>) |
| | >Re: Saving Images with Core Data (i.e., JPEG, TIFF, etc.) (From: mmalcolm crawford <email@hidden>) |