unable to update CLOB data using Commons DBCP connection.

[Arnav Velimala]

Am trying to do update a clob column using a connection object that is retrieved using Apache DBCP connection pooling.

Earlier, I've implemented connection pooling using this and it was working fine i.e am able to update CLOB. I switched to DBCP because I was getting java.sql.SQLException: ORA-01000: maximum open cursors exceeded. I've checked connection, resultSet, preparedStatement objects in all the DAOs. All the finally blocks have these cursors closed. Still am facing this error and so decided to switch to DBCP.

But, when I try to update CLOB, with this DBCP connection, the application just hangs at pstmt.executeUpdate().

Connection conn = null;
PreparedStatement pstmt = null;
CLOB clob = null;
String q = "UPDATE REPORT_TABLE SET RPT_FILE = ? WHERE RPT_SEQ_NUM = ?";
...
conn = DBConnection.getConnection();
pstmt = conn.prepareStatement(q);
clob = getCLOB(xmlReport, conn);
pstmt.setObject(1, clob);
pstmt.setString(2, reportSeqNo);

if (pstmt.executeUpdate() == 1) {
logger.logError("Report has been successfully UPDATED");
}
...

 

where getCLOB() method is:

   
private CLOB getCLOB(String xmlData, Connection conn) throws SQLException{
CLOB tempClob = null;
try{
// If the temporary CLOB has not yet been created, create new
tempClob = CLOB.createTemporary(conn, true, CLOB.DURATION_SESSION);

// Open the temporary CLOB in readwrite mode to enable writing
tempClob.open(CLOB.MODE_READWRITE);
// Get the output stream to write
Writer tempClobWriter = tempClob.getCharacterOutputStream();
// Write the data into the temporary CLOB
tempClobWriter.write(xmlData);

// Flush and close the stream
tempClobWriter.flush();
tempClobWriter.close();

// Close the temporary CLOB
tempClob.close();
} catch(SQLException sqlexp){
tempClob.freeTemporary();
sqlexp.printStackTrace();
} catch(Exception exp){
exp.printStackTrace();
tempClob.freeTemporary();
exp.printStackTrace();
}
return tempClob;
 

I've tried by passing the ((DelegatingConnection) conn).getInnermostDelegate() connection, but no use.

Also, the same is happening when I try to 'SELECT the CLOB column FOR UPDATE'.

Am using Oracle 9i and the JDBC Oracle Driver version is above 10.

Thanks