[jira] Commented: (CAY-1025) Do something about to-many prefetch limitations

From: Andrus Adamchik (JIRA) ("Andrus)
Date: Sun Oct 19 2008 - 08:18:11 EDT

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        [ https://issues.apache.org/cayenne/browse/CAY-1025?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13180#action_13180 ]

    Andrus Adamchik commented on CAY-1025:
    --------------------------------------

    Implemented a switch to joint prefetch on a local branch. Also implemented a related CAY-1128.

    TODO:

    1. need to test performance (e.g. vs 3.0M4 of the two solutions)
    2. Some tests are still failing. There seem to be a number of unaddressed JOINT prefetch limitations.

    > Do something about to-many prefetch limitations
    > -----------------------------------------------
    >
    > Key: CAY-1025
    > URL: https://issues.apache.org/cayenne/browse/CAY-1025
    > Project: Cayenne
    > Issue Type: Improvement
    > Components: Cayenne Core Library
    > Affects Versions: 1.2 [STABLE], 2.0 [STABLE], 3.0
    > Reporter: Andrus Adamchik
    > Assignee: Andrus Adamchik
    > Fix For: 3.0
    >
    >
    > 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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