db-jdo-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Alexander Bieber <a...@nightlabs.de>
Subject Re: [IMPORTANT] Fetch-depth
Date Mon, 16 Jan 2006 15:53:43 GMT
Thanks Craig for taking our arguments into account.
I'll still have a comment concerning the use case Jörg von Frantzuis 
submitted. His case is to limit the object-plan depth to a certain level 
while using FetchPlan.ALL as fetch-group. This is used for synchronizing 
data between datastores generically. In my oppinion we should think of 
an additional and optional (defaulting to -1) parameter to detachCopy - 
detachDepth - for this case.

Best regards

Alexander Bieber

Craig L Russell wrote:

> Javadogs,
> I've spent some time looking at the semantics of fetch-depth and now 
> agree with the critics of the change that I proposed back in the 
> infamous October 1, 2005 message to the expert group subject: *Re: 
> JDO2 §12.7.2: fetch-depth only for "recursive fetch group references"?*.
> I now believe it's impractical to use fetch-depth to mean the maximum 
> depth of the object graph reachable from the root object(s) field 
> because of several messages sent on the subject by Joerg von 
> Frantzuis, Alexander Bieber, and Marco Schultz.
> Briefly, the argument is that if fetch-depth limits the number 
> absolutely, then it's not possible easily to use the fetch-group to 
> add another field to a fetch plan simply by adding a fetch-group that 
> includes that field. Instead, a new fetch-group that changes the 
> fetch-depth must be used. And each new use-case needs to provide a 
> different fetch-depth number if another level of fetching is desired.
> I believe that the use of fetch-group to determine whether fields 
> (navigating relationships) are fetched should be natural, and that we 
> should therefore use fetch-depth for its original purpose of limiting 
> recursion.
> If you disagree with this position, please reply so we can move 
> forward and define the use of fetch-depth for recursion (as in the 
> original semantics of the attribute).
> Thanks,
> Craig
> Craig Russell
> Architect, Sun Java Enterprise System http://java.sun.com/products/jdo
> 408 276-5638 mailto:Craig.Russell@sun.com
> P.S. A good JDO? O, Gasp!

View raw message