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Re: Cached EO Objects
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Re: Cached EO Objects


  • Subject: Re: Cached EO Objects
  • From: Art Isbell <email@hidden>
  • Date: Sun, 25 Jul 2004 15:20:25 -1000

On Jul 25, 2004, at 2:31 PM, Lotsa Cabo wrote:

In this scenario, will the database be hit again?  If so, I assume EO
will evaluate the rows returned (a single row) and determine if the
object is already within the editing context.  Unfortunately, the trip
will already be made to the database.  Is this correct?

The determination will be made whether the fetched object is in the EO cache, not whether it's in a particular editing context. If it is and it's not older than the fetch timestamp for the editing context, the fetched object will be discarded by default with the existing cached object remaining valid.


Actually, I
assume that any time a fetch specification is used, the database will
be hit again, no?

I can't think of a situation in which this isn't true.

I guess the more I read about cached EO objects, the more confused I
become.

I repeat my recommendation that everyone who uses EOF download James Dempsey's WWDC FreshnessExplorer example. It really helps clear up this sort of confusion. After logging in to your Apple Developer Connection account, click "Download Software" and "WWDC - Enterprise/IT". Then download the topmost "629 - Using WebObjects EOF" disk image. I probably should have revisited FreshnessExplorer before attempting to reply :-)


For example, if I want all
"Messages" where the email address is from "1@2.3" I would assume that
the database will always be hit, even if I have objects cached in the
editing context.  I mean, if not, then how will it be possible to know
if there are any new objects in the database?

Exactly!

Aloha,
Art
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  • Follow-Ups:
    • Re: Cached EO Objects
      • From: Lotsa Cabo <email@hidden>
References: 
 >Cached EO Objects (From: Lotsa Cabo <email@hidden>)

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