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Reply-To: <mark@the-kruegers.name>
From: "Mark Stephen Krueger" <mark@the-kruegers.name>
To: <derby-user@db.apache.org>
Subject: SYSCS_DIAG.LOCK_TABLE keeps coming up enpty
Date: Sun, 3 Feb 2013 10:21:25 -0600
Message-ID: <01df01ce022a$848e3fc0$8daabf40$@the-kruegers.name>
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I'm trying to debug an issue with a deadlock with an EJB app running under
Glassfish 3.1.2.1.  The app uses entity beans and the entity manager.  I
want to view the lock table at various points so I wrote the following code.
The problem is everywhere I place a call to it, the lock table is always
coming back as empty (no rows). What am I missing?

    @Resource(mappedName="jdbc/myderbyjndi")
    private DataSource dataSource;

    ..

    private void dumpLockTable()
    {
        try ( Connection connection = dataSource.getConnection() )
        {
            PreparedStatement ps = connection.prepareStatement( "SELECT *
FROM SYSCS_DIAG.LOCK_TABLE" );
            ResultSet rs = ps.executeQuery();
            ResultSetMetaData rsmd = rs.getMetaData();
            int columns = rsmd.getColumnCount();            
            StringBuilder sb = new StringBuilder();
            sb.append( "Lock Table\n" );
            while( rs.next() )
            {
                for ( int col = 1; col <= columns; col++ )
                {
                    sb.append( rs.getString( col ) );
                    sb.append( "\t|" );
                }
                sb.append( "\n" );
            }
            logger.info( sb.toString() );
        }

        catch ( SQLException sqle )
        {
            logger.throwing( LOG_CLASS_NAME, "dumpLockTable", sqle );
        }
    }


I believe this is Derby 10.8.