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From "A B (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-1196) Network server closes prepared statements prematurely if exception occurs during OPNQRY and can cause "'Statement' already closed" exception on reexecution
Date Wed, 12 Apr 2006 00:42:23 GMT
    [ http://issues.apache.org/jira/browse/DERBY-1196?page=comments#action_12374120 ] 

A B commented on DERBY-1196:
----------------------------

As a follow-up comment, for what it's worth, I commented out two places where we have ASSERT
checks (one in ProjectRestrictResultSet and one in TableScanResultSet) and when I did, things
actually worked quite well.  Namely, the ODBC client was able to fetch the 1st and 2nd result
sets, then it received an "invalid cursor state" for the 3rd result set, and finally was able
to retrieve the 4th and 5th result sets without a problem.

This means that if I was to run the ODBC tests against an insane build, the queries would
actually "work" in a manner of speaking.

The comments for the ASSERT check in ProjectRestrictNode say the following:

		// REVISIT: through the direct DB API, this needs to be an
		// error, not an ASSERT; users can open twice. Only through JDBC
		// is access to open controlled and ensured valid.
		if (SanityManager.DEBUG)
		    SanityManager.ASSERT( ! isOpen, "ProjectRestrictResultSet already open");

Perhaps this part of the code has to be "revisited", as the comment says...?

I don't know if that's helpful or not; I'm just posting I've observed...

> Network server closes  prepared statements  prematurely if  exception occurs during OPNQRY
 and can cause "'Statement' already closed" exception on reexecution
> ---------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>          Key: DERBY-1196
>          URL: http://issues.apache.org/jira/browse/DERBY-1196
>      Project: Derby
>         Type: Bug

>   Components: Network Server
>     Versions: 10.2.0.0
>     Reporter: Kathey Marsden
>     Assignee: Kathey Marsden
>     Priority: Minor
>      Fix For: 10.2.0.0

>
> There is a bug in  Network Server that it closes prepared statements if
> an error occurs during execution on OPNQRY (usually PreparedStatement.execute())
> Basically the problem is this code in DRDAConnThread.java
> processCommands() which catches any exception that occurs during  OPNQRY
> and closes the prepared statement .  OPNQRY is just the statement execution and any statement
level exceptions should not cause the statement to be closed.
> catch (SQLException e)
>                     {
>                         writer.clearDSSesBackToMark(writerMark);
>                         try {
>                             // Try to cleanup if we hit an error.
>                             if (ps != null)
>                                 ps.close();
>                             writeOPNQFLRM(e);
>                         }
>                         catch (SQLException pse) {}
>                         errorInChain(e);
>                     }
> There are cases in jdbcapi/setTransactionIsolation when run with JCC that trigger this
case and yield a 
> 'Statement' already closed message. 
> This was the core issue with DERBY-1047 but there were problems with the DERBY-1047 Jira
entry in that the description of the problem was wrong and also the issue itself no longer
occurs with the fix for DERBY-1158.
> DERBY-1047 will be closed invalid and this issue will be used to  track  the fix.

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