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From "Daniel John Debrunner (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-997) ClassCastException when executing queries with aggregates in app servers
Date Wed, 01 Mar 2006 23:33:45 GMT
    [ http://issues.apache.org/jira/browse/DERBY-997?page=comments#action_12368394 ] 

Daniel John Debrunner commented on DERBY-997:

Chris Newell wrote: (on derby-user)

> I seem to have resolved my own issue as I was preparing a message to
> this list seeking help (thanks!). Having spent more hours than I care to
> admit trying to figure this out, and having seen another user in the
> list archive that had a similar problem with no solution provided, I
> thought that I'd post this with hopes of helping someone else that made
> the same stupid mistake.

[snip class cast exception ]

> The solution was:
> -------------------------
> I found that I had put a copy of derby.jar in both $TOMCAT/common/lib as
> well as $TOMCAT/webapps/[my app]/WEB-INF/lib. I removed the one under
> webapps and suddenly, as if by magic, I could count the rows in my
> table.... And the world seems like a nicer place.

> ClassCastException when executing queries with aggregates in app servers
> ------------------------------------------------------------------------
>          Key: DERBY-997
>          URL: http://issues.apache.org/jira/browse/DERBY-997
>      Project: Derby
>         Type: Bug
>   Components: SQL
>     Reporter: Daniel John Debrunner
>     Assignee: Daniel John Debrunner

> Classes that implement the aggregates such as MAX/MIN are loaded as user-defined classes
due to old support for user-defined aggregates.
> If the class loader setup running Derby is not well set up these classes are loaded in
a different class loader space to Derby's class leading to non-comparable classes due to the
the same class (dependend or subper-class, not sure which) being loaded twice.
> While this may be a user setup bug, it has occured frequently leading to wasted time
resolving the issue, it would be better if Derby ensured its classes were loaded consistently.

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