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Posted to commits@cayenne.apache.org by "Andrus Adamchik (JIRA)" <ji...@apache.org> on 2009/09/08 01:46:57 UTC
[jira] Commented: (CAY-1025) Do something about to-many prefetch
limitations
[ https://issues.apache.org/jira/browse/CAY-1025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12752287#action_12752287 ]
Andrus Adamchik commented on CAY-1025:
--------------------------------------
note that no switch to default joint prefetches occured (the performance won't be that great in this case). Instead disjoint algorithm was fixed, adding extra SQL joins for to-many
> Do something about to-many prefetch limitations
> -----------------------------------------------
>
> Key: CAY-1025
> URL: https://issues.apache.org/jira/browse/CAY-1025
> Project: Cayenne
> Issue Type: Improvement
> Components: Cayenne Core Library
> Affects Versions: 1.2 branch, 2.0 branch, 3.0
> Reporter: Andrus Adamchik
> Assignee: Andrus Adamchik
> Fix For: 3.0 beta 1
>
>
> http://cayenne.apache.org/doc/prefetching.html
> "PREFETCH LIMITATION: To-many relationships should not be prefetched if a query qualifier can potentially reduce a number of related objects, resulting in incorrect relationship list."
> This can bite an unsuspecting user... So we either
> 1. Address the core limitation by building a correct prefetch query (use subselect?)
> 2. Detect these cases and throw an exception
> 3. Detect these cases and silently drop a prefetch
> I should note that debugging these problems is very hard, as they look totally random until you get to the cause.
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