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From Edson Carlos Ericksson Richter <edson.rich...@mgrinformatica.com.br>
Subject Re: ClassCastException in CountAggregator
Date Thu, 15 Dec 2005 11:33:20 GMT
As stated in my previous mail, the connection pool is declared
<Resource auth="Container" description="Biblio" name="jdbc/Biblio"
type="javax.sql.DataSource" username="" password=""
driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
url="jdbc:derby:c:/projects/biblio/database;" maxActive="10" maxIdle="2"/>


And in web.xml I just have a resource-ref, as required by specs:

  <resource-ref>
    <description></description>
    <res-ref-name>jdbc/Biblio</res-ref-name>
    <res-type>javax.sql.DataSource</res-type>
    <res-auth>Container</res-auth>
  </resource-ref>


The code running is (it's a generic code I use to test queries, so don't 
be afraid about weird coding):

        <sql:query var="result" dataSource="jdbc/Biblio">
          select count(*) from my_table
        </sql:query>
        <table border='1' cellspacing='0' cellpadding='2'>
          <tr>
        <c:forEach items="${result.columnNames}" var="col">
          <th>${col}</th>
        </c:forEach>
          </tr>
        <c:forEach items="${result.rows}" var="row">
          <tr>
            <c:forEach items="${result.columnNames}" var="col">
              <td>${mgr:stripClob(row[col])}</td>
            </c:forEach>
          </tr>
        </c:forEach>
        </table>


The error occur at <sql:query...>, so rest of code is just here to 
illustrate usage.

At last, the derby.jar and derbypt_BR.jar are in 
$NETBEANS_HOME/enterprise2/jakarta-tomcat-5.5.9/commons/lib/, so classes 
are avaliable to the pool. If I remove them, I get problems with 
connection (and plain queries stop working).


I expect this helps... I will not have much time free help, but from 
times to times I'll check to see if there is anything I could contribute.

Best regards,

Edson Richter



Stanley Bradbury escreveu:

> edson.richter@mgrinformatica.com.br wrote:
>
>> Thank you all for the tips.
>>
>> Before giving up using derby, I have: 1) checked for older versions. 
>> No, there are none (in
>> real, I tried a fresh install of Tomcat). I double checked 
>> $JAVA_HOME/jre/lib/ext, and
>> tryied including install a new version of JDK (I was using 1.5.0_04 
>> and made a try with
>> 1.5.0_06 - no differences).
>> I tryied a simple JSP that take a connection from the pool and 
>> executed a simple select
>> count(*) from some_table and error is the same.
>>
>> Interesting is that I tryied Ij, and the error didn't occured.
>> But, Ij is not using pt_BR messages, and I suspect error is related 
>> (but then I give up: I
>> could not spent more than a couple of hours without sucess searching 
>> on the net - I searched
>> Google, MSN, Altavista). db.apache.org was unavaliable yesterday, and 
>> I could not search
>> mailing lists.
>>
>> So, without web support (even from the list), I could not defend 
>> Derby anymore in the
>> project, and manager directed all development to a comercial 
>> database, unfortunatelly.
>>
>> At all, thank you... But don't forget to check what could be wrong - 
>> there is a serious
>> erro/bugr in there.
>>
>> Details:
>>
>> - Tomcat 5.5.9 embedded in NetBeans 5.0 Beta 2
>> - Tomcat 5.5.7 embedded in NetBeans 4.1
>> - Connection obtained with 'jdbc:derby:c:/projects/biblio/database' 
>> (it's embedded) - Plain
>> queries works fine (select * from some_table)
>> - Aggregate count throw ClassCastException (select count(*) from 
>> some_table)
>>
>> Connection declaration:
>>
>> <Resource auth="Container" description="Biblio" name="jdbc/Biblio"
>> type="javax.sql.DataSource" username="" password=""
>> driverClassName="org.apache.derby.jdbc.EmbeddedDriver"
>> url="jdbc:derby:c:/projects/biblio/database;" maxActive="10" 
>> maxIdle="2"/>
>>
>> Here is stack trace:
>>
>> 08/12/2005 16:29:24 org.apache.catalina.core.ApplicationDispatcher 
>> invoke
>> SEVERE: Servlet.service() for servlet jsp threw exception
>> ERROR 38000: A exceção 'java.lang.ClassCastException:
>> org.apache.derby.impl.sql.execute.CountAggregator' foi emitida ao 
>> avaliar uma expressão.
>>        at 
>> org.apache.derby.iapi.error.StandardException.newException(Unknown 
>> Source)
>>        at 
>> org.apache.derby.iapi.error.StandardException.unexpectedUserException(Unknown 
>>
>> Source)
>>        at 
>> org.apache.derby.impl.sql.execute.GenericAggregator.getAggregatorInstance(Unknown

>>
>> Source)
>>        at 
>> org.apache.derby.impl.sql.execute.GenericAggregator.initialize(Unknown 
>> Source)
>>  
>>
> ......  SNIP ...
>
> Hi Edson -
>
> Could you help me setup a test case for this problem?  It would be 
> great if  you could provide a test case for the problem and file a 
> JIRA entry with the test case attached (please let me know if you can 
> do this).  It sounds, however, that you are working to a tight 
> timeframe so I am willing to attempt to create a test case but need 
> some additional information.
> I have not used NetBeans but know a bit about JSPs with Tomcat.  Could 
> you post the information I will need to perform the test you describe as:
>
> ".. I tryied a simple JSP that take a connection from the pool and 
> executed a simple select count(*) from some_table and error is the 
> same .."
>
> Here are the things I can think of that will be very helpful: + Having 
> the JSP code would be very helpful - would you post it?
> +  I need to know how the connection pool was defined (what entries 
> were placed in server.xml, the application deployment XML file and the 
> web.xml file). +  If there any other settings needed to setup the 
> connection pool in the Tomcat/NetBeans environment please include 
> those also.
> I have located another report of this stack trace when performing 
> 'select count(*)' in a different server that did not seem to relate to 
> codesets so I am hoping that  pt_BR is not required to debug this 
> problem.
>
> Thanks in advance
>
>
>


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